diff --git a/CHANGELOG.md b/CHANGELOG.md
index 57da05b..c303961 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,13 @@
+# 1.0.0
+
+* **New**: added the `fx()` and `wt()` extension functions to the `num` class to simplify the creation of `Fixed` and `Weight` cell sizes.
+* **New**: added the `cell()` and  `implicitCell()` extension functions to the `Widget` class to simplify the creation of `Cell` and `Cell.implicit` widgets.
+* Minimum Flutter SDK is **3.0.0**
+
 # 0.9.0
 
-Update version
+* Version update
 
 # 0.0.9
 
-First public release
+* **New**: first public release
diff --git a/README.md b/README.md
index cc96fe3..85defb5 100644
--- a/README.md
+++ b/README.md
@@ -81,6 +81,18 @@ GridPad(
 );
 ```
 
+Instead of using `Weight` and `Fixed` explicitly, the appropriate extension functions can be used:
+
+```dart
+GridPad(
+  gridPadCells: GridPadCellsBuilder(rowCount: 3, columnCount: 4)
+    .rowSize(0, 2.wt())
+    .columnSize(3, 90.fx())
+    .build(),
+  children: [],
+);
+```
+
 ![custom_define_grid_dark](https://github.com/landarskiy/gridpad_flutter/assets/2251498/4a769913-c84d-427c-8f1b-10a1574d2bf2)
 
 The algorithm for allocating available space between cells:
@@ -136,6 +148,18 @@ GridPad(
 );
 ```
 
+Alternatively, instead of the Cell widget, `Widget.cell()` extension functions can be applied:
+
+```dart
+GridPad(
+  gridPadCells: GridPadCells.gridSize(rowCount: 3, columnCount: 4),       
+  children: [
+    ChildWidget().cell(row: 1, column: 2),
+    ChildWidget().cell(row: 0, column: 1),
+  ],
+);
+```
+
 ![place_items_specific_dark](https://github.com/landarskiy/gridpad_flutter/assets/2251498/f1bf96e4-f7d2-4614-bda6-4e90ff18a741)
 
 > :warning: A cell can contain more than one item. The draw order will be the same as the place
@@ -216,13 +240,7 @@ GridPad(
   children: [
     // will be skipped in a drawing process because the item is placed in the column range [3;5] 
     // but the maximum allowable is 3
-    Cell(
-      row: 1,
-      column: 3
-      rowSpan: 1,
-      columnSpan: 3,
-      child: ChildWidget(),
-    ), 
+    ChildWidget().cell(row: 1, column: 3, rowSpan: 1, columnSpan: 3),
   ],
 );
 ```
@@ -238,7 +256,7 @@ parameter - **anchor**. The anchor is the point in the corner from which the spa
 The value depends on `horizontalPolicy` and `verticalPolicy` values in the `placementPolicy`
 property.
 
-![anchor](https://github.com/landarskiy/gridpad_flutter/assets/2251498/1c7e5df7-e311-4d21-b86b-e0304c9f4069)
+![anchor](https://github.com/touchlane/gridpad_flutter/assets/2251498/9ec4d525-5450-4aba-a456-3896ce553db4)
 
 ## Layout Direction
 
diff --git a/example/lib/components/blueprint.dart b/example/lib/components/blueprint.dart
index 9def9cc..c2e06d6 100644
--- a/example/lib/components/blueprint.dart
+++ b/example/lib/components/blueprint.dart
@@ -3,7 +3,7 @@ import 'package:flutter/material.dart';
 import '../theme.dart';
 
 class BlueprintBox extends StatelessWidget {
-  const BlueprintBox({Key? key}) : super(key: key);
+  const BlueprintBox({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -29,7 +29,7 @@ class BlueprintBox extends StatelessWidget {
 class ContentBlueprintBox extends StatelessWidget {
   final String text;
 
-  const ContentBlueprintBox({Key? key, this.text = ''}) : super(key: key);
+  const ContentBlueprintBox({super.key, this.text = ''});
 
   @override
   Widget build(BuildContext context) {
diff --git a/example/lib/components/engineering_calculator_pad.dart b/example/lib/components/engineering_calculator_pad.dart
index 4efa029..7a47243 100644
--- a/example/lib/components/engineering_calculator_pad.dart
+++ b/example/lib/components/engineering_calculator_pad.dart
@@ -5,7 +5,7 @@ import 'package:grid_pad/grid_pad.dart';
 import 'pad_button.dart';
 
 class EngineeringCalculatorPad extends StatelessWidget {
-  const EngineeringCalculatorPad({Key? key}) : super(key: key);
+  const EngineeringCalculatorPad({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -19,30 +19,21 @@ class EngineeringCalculatorPad extends StatelessWidget {
       ),
       child: GridPad(
         gridPadCells: GridPadCellsBuilder(rowCount: 5, columnCount: 5)
-            .rowSize(0, const Fixed(48))
+            .rowSize(0, 48.fx())
             .build(),
         children: [
           //BG space
-          Cell(
-            row: 1,
-            column: 0,
-            rowSpan: 4,
-            columnSpan: 3,
-            child: DecoratedBox(
-              decoration: BoxDecoration(
-                color: padTheme.colors.numBackground,
-                shape: BoxShape.rectangle,
-                borderRadius: const BorderRadius.all(Radius.circular(8.0)),
-              ),
-              child: Container(),
+          DecoratedBox(
+            decoration: BoxDecoration(
+              color: padTheme.colors.numBackground,
+              shape: BoxShape.rectangle,
+              borderRadius: const BorderRadius.all(Radius.circular(8.0)),
             ),
-          ),
-          Cell(
-            row: 0,
-            column: 0,
-            child: _FunctionTheme(
-                child: SmallTextPadButton('sin', onPressed: () {})),
-          ),
+            child: Container(),
+          ).cell(row: 1, column: 0, rowSpan: 4, columnSpan: 3),
+          _FunctionTheme(
+            child: SmallTextPadButton('sin', onPressed: () {}),
+          ).cell(row: 0, column: 0),
           _FunctionTheme(child: SmallTextPadButton('cos', onPressed: () {})),
           _FunctionTheme(child: SmallTextPadButton('log', onPressed: () {})),
           _FunctionTheme(child: SmallTextPadButton('π', onPressed: () {})),
@@ -133,7 +124,7 @@ class EngineeringCalculatorPadTheme {
 class _FunctionTheme extends StatelessWidget {
   final Widget child;
 
-  const _FunctionTheme({Key? key, required this.child}) : super(key: key);
+  const _FunctionTheme({required this.child});
 
   @override
   Widget build(BuildContext context) {
@@ -153,7 +144,7 @@ class _FunctionTheme extends StatelessWidget {
 class _ActionTheme extends StatelessWidget {
   final Widget child;
 
-  const _ActionTheme({Key? key, required this.child}) : super(key: key);
+  const _ActionTheme({required this.child});
 
   @override
   Widget build(BuildContext context) {
@@ -173,7 +164,7 @@ class _ActionTheme extends StatelessWidget {
 class _RemoveTheme extends StatelessWidget {
   final Widget child;
 
-  const _RemoveTheme({Key? key, required this.child}) : super(key: key);
+  const _RemoveTheme({required this.child});
 
   @override
   Widget build(BuildContext context) {
diff --git a/example/lib/components/interactive_pin_pad.dart b/example/lib/components/interactive_pin_pad.dart
index bfece1e..d6456a5 100644
--- a/example/lib/components/interactive_pin_pad.dart
+++ b/example/lib/components/interactive_pin_pad.dart
@@ -3,7 +3,7 @@ import 'package:flutter/material.dart';
 import 'pin_pad.dart';
 
 class InteractivePinPad extends StatefulWidget {
-  const InteractivePinPad({Key? key}) : super(key: key);
+  const InteractivePinPad({super.key});
 
   @override
   State<InteractivePinPad> createState() => _InteractivePinPadState();
diff --git a/example/lib/components/pad_button.dart b/example/lib/components/pad_button.dart
index 42b26b3..ad804bc 100644
--- a/example/lib/components/pad_button.dart
+++ b/example/lib/components/pad_button.dart
@@ -7,9 +7,9 @@ class IconPadButton extends StatelessWidget {
 
   const IconPadButton(
     this.iconData, {
-    Key? key,
+    super.key,
     this.onPressed,
-  }) : super(key: key);
+  });
 
   @override
   Widget build(BuildContext context) {
@@ -31,9 +31,9 @@ class LargeTextPadButton extends StatelessWidget {
 
   const LargeTextPadButton(
     this.text, {
-    Key? key,
+    super.key,
     this.onPressed,
-  }) : super(key: key);
+  });
 
   @override
   Widget build(BuildContext context) {
@@ -51,9 +51,9 @@ class MediumTextPadButton extends StatelessWidget {
 
   const MediumTextPadButton(
     this.text, {
-    Key? key,
+    super.key,
     this.onPressed,
-  }) : super(key: key);
+  });
 
   @override
   Widget build(BuildContext context) {
@@ -71,9 +71,9 @@ class SmallTextPadButton extends StatelessWidget {
 
   const SmallTextPadButton(
     this.text, {
-    Key? key,
+    super.key,
     this.onPressed,
-  }) : super(key: key);
+  });
 
   @override
   Widget build(BuildContext context) {
@@ -91,11 +91,11 @@ class TextPadButton extends StatelessWidget {
   final VoidCallback? onPressed;
 
   const TextPadButton({
-    Key? key,
+    super.key,
     required this.text,
     this.style,
     this.onPressed,
-  }) : super(key: key);
+  });
 
   @override
   Widget build(BuildContext context) {
@@ -115,8 +115,7 @@ class PadButton extends StatelessWidget {
   final Widget child;
   final VoidCallback? onPressed;
 
-  const PadButton({Key? key, this.onPressed, required this.child})
-      : super(key: key);
+  const PadButton({super.key, this.onPressed, required this.child});
 
   @override
   Widget build(BuildContext context) {
diff --git a/example/lib/components/pin_pad.dart b/example/lib/components/pin_pad.dart
index fed7991..b850267 100644
--- a/example/lib/components/pin_pad.dart
+++ b/example/lib/components/pin_pad.dart
@@ -7,7 +7,7 @@ import 'pad_button.dart';
 class PinPad extends StatelessWidget {
   final PadActionCallback? callback;
 
-  const PinPad({Key? key, this.callback}) : super(key: key);
+  const PinPad({super.key, this.callback});
 
   @override
   Widget build(BuildContext context) {
@@ -25,14 +25,10 @@ class PinPad extends StatelessWidget {
           verticalPolicy: VerticalPolicy.bottomTop,
         ),
         children: [
-          Cell(
-            row: 3,
-            column: 1,
-            child: LargeTextPadButton(
-              '0',
-              onPressed: () => callback?.call('0'),
-            ),
-          ),
+          LargeTextPadButton(
+            '0',
+            onPressed: () => callback?.call('0'),
+          ).cell(row: 3, column: 1),
           PadThemeProvider(
             theme: PadButtonTheme(
               colors: PadButtonColors(
diff --git a/example/lib/components/simple_calculator_pad.dart b/example/lib/components/simple_calculator_pad.dart
index 85b0e94..0f7bc3d 100644
--- a/example/lib/components/simple_calculator_pad.dart
+++ b/example/lib/components/simple_calculator_pad.dart
@@ -5,7 +5,7 @@ import 'package:grid_pad/grid_pad.dart';
 import 'pad_button.dart';
 
 class SimpleCalculatorPad extends StatelessWidget {
-  const SimpleCalculatorPad({Key? key}) : super(key: key);
+  const SimpleCalculatorPad({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -35,21 +35,11 @@ class SimpleCalculatorPad extends StatelessWidget {
           LargeTextPadButton('1', onPressed: () {}),
           LargeTextPadButton('2', onPressed: () {}),
           LargeTextPadButton('3', onPressed: () {}),
-          Cell.implicit(
-            rowSpan: 2,
-            child: _ActionTheme(
-              child: LargeTextPadButton('=', onPressed: () {}),
-            ),
-          ),
-          Cell(
-            row: 4,
-            column: 0,
-            child: LargeTextPadButton('.', onPressed: () {}),
-          ),
-          Cell.implicit(
-            columnSpan: 2,
-            child: LargeTextPadButton('0', onPressed: () {}),
-          ),
+          _ActionTheme(
+            child: LargeTextPadButton('=', onPressed: () {}),
+          ).implicitCell(rowSpan: 2),
+          LargeTextPadButton('.', onPressed: () {}).cell(row: 4, column: 0),
+          LargeTextPadButton('0', onPressed: () {}).implicitCell(columnSpan: 2),
         ],
       ),
     );
@@ -115,7 +105,7 @@ extension _ThemeExtension on BuildContext {
 class _ActionTheme extends StatelessWidget {
   final Widget child;
 
-  const _ActionTheme({Key? key, required this.child}) : super(key: key);
+  const _ActionTheme({required this.child});
 
   @override
   Widget build(BuildContext context) {
@@ -135,7 +125,7 @@ class _ActionTheme extends StatelessWidget {
 class _RemoveTheme extends StatelessWidget {
   final Widget child;
 
-  const _RemoveTheme({Key? key, required this.child}) : super(key: key);
+  const _RemoveTheme({required this.child});
 
   @override
   Widget build(BuildContext context) {
diff --git a/example/lib/components/simple_priority_calculator_pad.dart b/example/lib/components/simple_priority_calculator_pad.dart
index fa5627a..bedf7c4 100644
--- a/example/lib/components/simple_priority_calculator_pad.dart
+++ b/example/lib/components/simple_priority_calculator_pad.dart
@@ -5,7 +5,7 @@ import 'package:grid_pad/grid_pad.dart';
 import 'pad_button.dart';
 
 class SimplePriorityCalculatorPad extends StatelessWidget {
-  const SimplePriorityCalculatorPad({Key? key}) : super(key: key);
+  const SimplePriorityCalculatorPad({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -19,22 +19,16 @@ class SimplePriorityCalculatorPad extends StatelessWidget {
       ),
       child: GridPad(
         gridPadCells: GridPadCellsBuilder(rowCount: 5, columnCount: 5)
-            .rowSize(0, const Fixed(48))
+            .rowSize(0, 48.fx())
             .build(),
         children: [
           _RemoveTheme(child: MediumTextPadButton('C', onPressed: () {})),
-          Cell.implicit(
-            columnSpan: 2,
-            child: _ActionTheme(
-              child: MediumTextPadButton('(', onPressed: () {}),
-            ),
-          ),
-          Cell.implicit(
-            columnSpan: 2,
-            child: _ActionTheme(
-              child: MediumTextPadButton(')', onPressed: () {}),
-            ),
-          ),
+          _ActionTheme(
+            child: MediumTextPadButton('(', onPressed: () {}),
+          ).implicitCell(columnSpan: 2),
+          _ActionTheme(
+            child: MediumTextPadButton(')', onPressed: () {}),
+          ).implicitCell(columnSpan: 2),
           LargeTextPadButton('7', onPressed: () {}),
           LargeTextPadButton('8', onPressed: () {}),
           LargeTextPadButton('9', onPressed: () {}),
@@ -43,38 +37,21 @@ class SimplePriorityCalculatorPad extends StatelessWidget {
           LargeTextPadButton('4', onPressed: () {}),
           LargeTextPadButton('5', onPressed: () {}),
           LargeTextPadButton('6', onPressed: () {}),
-          Cell.implicit(
-            rowSpan: 2,
-            child: _ActionTheme(
-              child: LargeTextPadButton('-', onPressed: () {}),
-            ),
-          ),
-          Cell.implicit(
-            rowSpan: 2,
-            child: _ActionTheme(
-              child: LargeTextPadButton('+', onPressed: () {}),
-            ),
-          ),
-          Cell(
-            row: 3,
-            column: 0,
-            child: LargeTextPadButton('1', onPressed: () {}),
-          ),
+          _ActionTheme(
+            child: LargeTextPadButton('-', onPressed: () {}),
+          ).implicitCell(rowSpan: 2),
+          _ActionTheme(
+            child: LargeTextPadButton('+', onPressed: () {}),
+          ).implicitCell(rowSpan: 2),
+          LargeTextPadButton('1', onPressed: () {}).cell(row: 3, column: 0),
           LargeTextPadButton('2', onPressed: () {}),
           LargeTextPadButton('3', onPressed: () {}),
-          Cell(
-            row: 4,
-            column: 0,
-            child: LargeTextPadButton('0', onPressed: () {}),
-          ),
+          LargeTextPadButton('0', onPressed: () {}).cell(row: 4, column: 0),
           LargeTextPadButton('.', onPressed: () {}),
           _RemoveTheme(child: IconPadButton(Icons.backspace, onPressed: () {})),
-          Cell.implicit(
-            columnSpan: 2,
-            child: _ActionTheme(
-              child: LargeTextPadButton('=', onPressed: () {}),
-            ),
-          ),
+          _ActionTheme(
+            child: LargeTextPadButton('=', onPressed: () {}),
+          ).implicitCell(columnSpan: 2),
         ],
       ),
     );
@@ -140,7 +117,7 @@ extension _ThemeExtension on BuildContext {
 class _ActionTheme extends StatelessWidget {
   final Widget child;
 
-  const _ActionTheme({Key? key, required this.child}) : super(key: key);
+  const _ActionTheme({required this.child});
 
   @override
   Widget build(BuildContext context) {
@@ -160,7 +137,7 @@ class _ActionTheme extends StatelessWidget {
 class _RemoveTheme extends StatelessWidget {
   final Widget child;
 
-  const _RemoveTheme({Key? key, required this.child}) : super(key: key);
+  const _RemoveTheme({required this.child});
 
   @override
   Widget build(BuildContext context) {
diff --git a/example/lib/main.dart b/example/lib/main.dart
index fc8a33b..427eb4e 100644
--- a/example/lib/main.dart
+++ b/example/lib/main.dart
@@ -38,7 +38,7 @@ class MyApp extends StatelessWidget {
 }
 
 class HomePage extends StatelessWidget {
-  const HomePage({Key? key}) : super(key: key);
+  const HomePage({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -52,7 +52,7 @@ class HomePage extends StatelessWidget {
 }
 
 class ListOfPads extends StatelessWidget {
-  const ListOfPads({Key? key}) : super(key: key);
+  const ListOfPads({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -84,10 +84,10 @@ class PadCard extends StatelessWidget {
   final Widget child;
 
   const PadCard({
-    Key? key,
+    super.key,
     required this.ratio,
     required this.child,
-  }) : super(key: key);
+  });
 
   @override
   Widget build(BuildContext context) {
@@ -112,11 +112,11 @@ class BlueprintCard extends StatelessWidget {
   final Widget child;
 
   const BlueprintCard({
-    Key? key,
+    super.key,
     this.ratio = 1,
     this.title,
     required this.child,
-  }) : super(key: key);
+  });
 
   @override
   Widget build(BuildContext context) {
@@ -156,10 +156,10 @@ class WeightGrid extends StatelessWidget {
   final int columnCount;
 
   const WeightGrid({
-    Key? key,
+    super.key,
     required this.rowCount,
     required this.columnCount,
-  }) : super(key: key);
+  });
 
   @override
   Widget build(BuildContext context) {
@@ -176,7 +176,7 @@ class WeightGrid extends StatelessWidget {
 }
 
 class InteractivePinPadCard extends StatelessWidget {
-  const InteractivePinPadCard({Key? key}) : super(key: key);
+  const InteractivePinPadCard({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -202,7 +202,7 @@ class InteractivePinPadCard extends StatelessWidget {
 }
 
 class EngineeringCalculatorPadCard extends StatelessWidget {
-  const EngineeringCalculatorPadCard({Key? key}) : super(key: key);
+  const EngineeringCalculatorPadCard({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -226,7 +226,7 @@ class EngineeringCalculatorPadCard extends StatelessWidget {
 }
 
 class SimplePriorityCalculatorPadCard extends StatelessWidget {
-  const SimplePriorityCalculatorPadCard({Key? key}) : super(key: key);
+  const SimplePriorityCalculatorPadCard({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -248,7 +248,7 @@ class SimplePriorityCalculatorPadCard extends StatelessWidget {
 }
 
 class SimpleCalculatorPadCard extends StatelessWidget {
-  const SimpleCalculatorPadCard({Key? key}) : super(key: key);
+  const SimpleCalculatorPadCard({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -270,7 +270,7 @@ class SimpleCalculatorPadCard extends StatelessWidget {
 }
 
 class SimpleBlueprintCard extends StatelessWidget {
-  const SimpleBlueprintCard({Key? key}) : super(key: key);
+  const SimpleBlueprintCard({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -285,7 +285,7 @@ class SimpleBlueprintCard extends StatelessWidget {
 }
 
 class CustomSizeBlueprintCard extends StatelessWidget {
-  const CustomSizeBlueprintCard({Key? key}) : super(key: key);
+  const CustomSizeBlueprintCard({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -293,8 +293,8 @@ class CustomSizeBlueprintCard extends StatelessWidget {
       ratio: 1.5,
       child: GridPad(
         gridPadCells: GridPadCellsBuilder(rowCount: 3, columnCount: 4)
-            .rowSize(0, const Weight(2))
-            .columnSize(3, const Fixed(30))
+            .rowSize(0, 2.wt())
+            .columnSize(3, 30.fx())
             .build(),
         children: [for (var i = 0; i < 12; i++) const BlueprintBox()],
       ),
@@ -303,7 +303,7 @@ class CustomSizeBlueprintCard extends StatelessWidget {
 }
 
 class SimpleBlueprintCardWithContent extends StatelessWidget {
-  const SimpleBlueprintCardWithContent({Key? key}) : super(key: key);
+  const SimpleBlueprintCardWithContent({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -331,7 +331,7 @@ class SimpleBlueprintCardWithContent extends StatelessWidget {
 }
 
 class SimpleBlueprintCardWithContentMixOrdering extends StatelessWidget {
-  const SimpleBlueprintCardWithContentMixOrdering({Key? key}) : super(key: key);
+  const SimpleBlueprintCardWithContentMixOrdering({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -367,7 +367,7 @@ class SimpleBlueprintCardWithContentMixOrdering extends StatelessWidget {
 }
 
 class SimpleBlueprintCardWithSpansOverlapped extends StatelessWidget {
-  const SimpleBlueprintCardWithSpansOverlapped({Key? key}) : super(key: key);
+  const SimpleBlueprintCardWithSpansOverlapped({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -411,8 +411,7 @@ class SimpleBlueprintCardPolicy extends StatelessWidget {
 
   const SimpleBlueprintCardPolicy(
       this.mainAxis, this.horizontalPolicy, this.verticalPolicy,
-      {Key? key})
-      : super(key: key);
+      {super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -448,7 +447,7 @@ class SimpleBlueprintCardPolicy extends StatelessWidget {
 }
 
 class SimpleBlueprintCardPolicyHorizontalSeTb extends StatelessWidget {
-  const SimpleBlueprintCardPolicyHorizontalSeTb({Key? key}) : super(key: key);
+  const SimpleBlueprintCardPolicyHorizontalSeTb({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -461,8 +460,7 @@ class SimpleBlueprintCardPolicyHorizontalSeTb extends StatelessWidget {
 }
 
 class SimpleBlueprintCardPolicyHorizontalSeTbRtl extends StatelessWidget {
-  const SimpleBlueprintCardPolicyHorizontalSeTbRtl({Key? key})
-      : super(key: key);
+  const SimpleBlueprintCardPolicyHorizontalSeTbRtl({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -474,7 +472,7 @@ class SimpleBlueprintCardPolicyHorizontalSeTbRtl extends StatelessWidget {
 }
 
 class SimpleBlueprintCardPolicyHorizontalEsTb extends StatelessWidget {
-  const SimpleBlueprintCardPolicyHorizontalEsTb({Key? key}) : super(key: key);
+  const SimpleBlueprintCardPolicyHorizontalEsTb({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -487,7 +485,7 @@ class SimpleBlueprintCardPolicyHorizontalEsTb extends StatelessWidget {
 }
 
 class SimpleBlueprintCardPolicyHorizontalSeBt extends StatelessWidget {
-  const SimpleBlueprintCardPolicyHorizontalSeBt({Key? key}) : super(key: key);
+  const SimpleBlueprintCardPolicyHorizontalSeBt({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -500,7 +498,7 @@ class SimpleBlueprintCardPolicyHorizontalSeBt extends StatelessWidget {
 }
 
 class SimpleBlueprintCardPolicyHorizontalEsBt extends StatelessWidget {
-  const SimpleBlueprintCardPolicyHorizontalEsBt({Key? key}) : super(key: key);
+  const SimpleBlueprintCardPolicyHorizontalEsBt({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -513,7 +511,7 @@ class SimpleBlueprintCardPolicyHorizontalEsBt extends StatelessWidget {
 }
 
 class SimpleBlueprintCardPolicyVerticalSeTb extends StatelessWidget {
-  const SimpleBlueprintCardPolicyVerticalSeTb({Key? key}) : super(key: key);
+  const SimpleBlueprintCardPolicyVerticalSeTb({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -526,7 +524,7 @@ class SimpleBlueprintCardPolicyVerticalSeTb extends StatelessWidget {
 }
 
 class SimpleBlueprintCardPolicyVerticalEsTb extends StatelessWidget {
-  const SimpleBlueprintCardPolicyVerticalEsTb({Key? key}) : super(key: key);
+  const SimpleBlueprintCardPolicyVerticalEsTb({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -539,7 +537,7 @@ class SimpleBlueprintCardPolicyVerticalEsTb extends StatelessWidget {
 }
 
 class SimpleBlueprintCardPolicyVerticalSeBt extends StatelessWidget {
-  const SimpleBlueprintCardPolicyVerticalSeBt({Key? key}) : super(key: key);
+  const SimpleBlueprintCardPolicyVerticalSeBt({super.key});
 
   @override
   Widget build(BuildContext context) {
@@ -552,7 +550,7 @@ class SimpleBlueprintCardPolicyVerticalSeBt extends StatelessWidget {
 }
 
 class SimpleBlueprintCardPolicyVerticalEsBt extends StatelessWidget {
-  const SimpleBlueprintCardPolicyVerticalEsBt({Key? key}) : super(key: key);
+  const SimpleBlueprintCardPolicyVerticalEsBt({super.key});
 
   @override
   Widget build(BuildContext context) {
diff --git a/example/pubspec.lock b/example/pubspec.lock
index 5ab9d37..b0a453d 100644
--- a/example/pubspec.lock
+++ b/example/pubspec.lock
@@ -37,18 +37,18 @@ packages:
     dependency: transitive
     description:
       name: collection
-      sha256: "4a07be6cb69c84d677a6c3096fcf960cc3285a8330b4603e0d463d15d9bd934c"
+      sha256: ee67cb0715911d28db6bf4af1026078bd6f0128b07a5f66fb2ed94ec6783c09a
       url: "https://pub.dev"
     source: hosted
-    version: "1.17.1"
+    version: "1.18.0"
   cupertino_icons:
     dependency: "direct main"
     description:
       name: cupertino_icons
-      sha256: e35129dc44c9118cee2a5603506d823bab99c68393879edb440e0090d07586be
+      sha256: d57953e10f9f8327ce64a508a355f0b1ec902193f66288e8cb5070e7c47eeb2d
       url: "https://pub.dev"
     source: hosted
-    version: "1.0.5"
+    version: "1.0.6"
   fake_async:
     dependency: transitive
     description:
@@ -66,10 +66,10 @@ packages:
     dependency: "direct dev"
     description:
       name: flutter_lints
-      sha256: aeb0b80a8b3709709c9cc496cdc027c5b3216796bc0af0ce1007eaf24464fd4c
+      sha256: e2a421b7e59244faef694ba7b30562e489c2b489866e505074eb005cd7060db7
       url: "https://pub.dev"
     source: hosted
-    version: "2.0.1"
+    version: "3.0.1"
   flutter_test:
     dependency: "direct dev"
     description: flutter
@@ -81,55 +81,71 @@ packages:
       path: ".."
       relative: true
     source: path
-    version: "0.9.0"
-  js:
+    version: "1.0.0"
+  leak_tracker:
+    dependency: transitive
+    description:
+      name: leak_tracker
+      sha256: "78eb209deea09858f5269f5a5b02be4049535f568c07b275096836f01ea323fa"
+      url: "https://pub.dev"
+    source: hosted
+    version: "10.0.0"
+  leak_tracker_flutter_testing:
+    dependency: transitive
+    description:
+      name: leak_tracker_flutter_testing
+      sha256: b46c5e37c19120a8a01918cfaf293547f47269f7cb4b0058f21531c2465d6ef0
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.0.1"
+  leak_tracker_testing:
     dependency: transitive
     description:
-      name: js
-      sha256: f2c445dce49627136094980615a031419f7f3eb393237e4ecd97ac15dea343f3
+      name: leak_tracker_testing
+      sha256: a597f72a664dbd293f3bfc51f9ba69816f84dcd403cdac7066cb3f6003f3ab47
       url: "https://pub.dev"
     source: hosted
-    version: "0.6.7"
+    version: "2.0.1"
   lints:
     dependency: transitive
     description:
       name: lints
-      sha256: "6b0206b0bf4f04961fc5438198ccb3a885685cd67d4d4a32cc20ad7f8adbe015"
+      sha256: cbf8d4b858bb0134ef3ef87841abdf8d63bfc255c266b7bf6b39daa1085c4290
       url: "https://pub.dev"
     source: hosted
-    version: "2.1.0"
+    version: "3.0.0"
   matcher:
     dependency: transitive
     description:
       name: matcher
-      sha256: "6501fbd55da300384b768785b83e5ce66991266cec21af89ab9ae7f5ce1c4cbb"
+      sha256: d2323aa2060500f906aa31a895b4030b6da3ebdcc5619d14ce1aada65cd161cb
       url: "https://pub.dev"
     source: hosted
-    version: "0.12.15"
+    version: "0.12.16+1"
   material_color_utilities:
     dependency: transitive
     description:
       name: material_color_utilities
-      sha256: d92141dc6fe1dad30722f9aa826c7fbc896d021d792f80678280601aff8cf724
+      sha256: "0e0a020085b65b6083975e499759762399b4475f766c21668c4ecca34ea74e5a"
       url: "https://pub.dev"
     source: hosted
-    version: "0.2.0"
+    version: "0.8.0"
   meta:
     dependency: transitive
     description:
       name: meta
-      sha256: "3c74dbf8763d36539f114c799d8a2d87343b5067e9d796ca22b5eb8437090ee3"
+      sha256: d584fa6707a52763a52446f02cc621b077888fb63b93bbcb1143a7be5a0c0c04
       url: "https://pub.dev"
     source: hosted
-    version: "1.9.1"
+    version: "1.11.0"
   path:
     dependency: transitive
     description:
       name: path
-      sha256: "8829d8a55c13fc0e37127c29fedf290c102f4e40ae94ada574091fe0ff96c917"
+      sha256: "087ce49c3f0dc39180befefc60fdb4acd8f8620e5682fe2476afd0b3688bb4af"
       url: "https://pub.dev"
     source: hosted
-    version: "1.8.3"
+    version: "1.9.0"
   sky_engine:
     dependency: transitive
     description: flutter
@@ -139,26 +155,26 @@ packages:
     dependency: transitive
     description:
       name: source_span
-      sha256: dd904f795d4b4f3b870833847c461801f6750a9fa8e61ea5ac53f9422b31f250
+      sha256: "53e943d4206a5e30df338fd4c6e7a077e02254531b138a15aec3bd143c1a8b3c"
       url: "https://pub.dev"
     source: hosted
-    version: "1.9.1"
+    version: "1.10.0"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
-      sha256: c3c7d8edb15bee7f0f74debd4b9c5f3c2ea86766fe4178eb2a18eb30a0bdaed5
+      sha256: "73713990125a6d93122541237550ee3352a2d84baad52d375a4cad2eb9b7ce0b"
       url: "https://pub.dev"
     source: hosted
-    version: "1.11.0"
+    version: "1.11.1"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
-      sha256: "83615bee9045c1d322bbbd1ba209b7a749c2cbcdcb3fdd1df8eb488b3279c1c8"
+      sha256: ba2aa5d8cc609d96bbb2899c28934f9e1af5cddbd60a827822ea467161eb54e7
       url: "https://pub.dev"
     source: hosted
-    version: "2.1.1"
+    version: "2.1.2"
   string_scanner:
     dependency: transitive
     description:
@@ -179,10 +195,10 @@ packages:
     dependency: transitive
     description:
       name: test_api
-      sha256: eb6ac1540b26de412b3403a163d919ba86f6a973fe6cc50ae3541b80092fdcfb
+      sha256: "5c2f730018264d276c20e4f1503fd1308dfbbae39ec8ee63c5236311ac06954b"
       url: "https://pub.dev"
     source: hosted
-    version: "0.5.1"
+    version: "0.6.1"
   vector_math:
     dependency: transitive
     description:
@@ -191,6 +207,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.1.4"
+  vm_service:
+    dependency: transitive
+    description:
+      name: vm_service
+      sha256: b3d56ff4341b8f182b96aceb2fa20e3dcb336b9f867bc0eafc0de10f1048e957
+      url: "https://pub.dev"
+    source: hosted
+    version: "13.0.0"
 sdks:
-  dart: ">=3.0.0-417 <4.0.0"
+  dart: ">=3.2.0-0 <4.0.0"
   flutter: ">=1.17.0"
diff --git a/example/pubspec.yaml b/example/pubspec.yaml
index f7df59e..79582a3 100644
--- a/example/pubspec.yaml
+++ b/example/pubspec.yaml
@@ -6,7 +6,7 @@ publish_to: 'none'
 version: 1.0.0+1
 
 environment:
-  sdk: '>=2.18.6 <4.0.0'
+  sdk: '>=3.0.0 <4.0.0'
 
 dependencies:
   flutter:
@@ -20,7 +20,7 @@ dev_dependencies:
   flutter_test:
     sdk: flutter
 
-  flutter_lints: ^2.0.0
+  flutter_lints: ^3.0.1
 
 flutter:
 
diff --git a/lib/grid_pad_cells.dart b/lib/grid_pad_cells.dart
index 250b2ca..89c9514 100644
--- a/lib/grid_pad_cells.dart
+++ b/lib/grid_pad_cells.dart
@@ -151,17 +151,13 @@ extension GridPadCellSizeExtension on Iterable<GridPadCellSize> {
     double totalWeightSize = 0;
     double totalFixedSize = 0;
     for (var cellSize in this) {
-      switch (cellSize.runtimeType) {
-        case Weight:
-          totalWeightSize += (cellSize as Weight).size;
+      switch (cellSize) {
+        case Weight():
+          totalWeightSize += cellSize.size;
           break;
-        case Fixed:
-          totalFixedSize += (cellSize as Fixed).size;
+        case Fixed():
+          totalFixedSize += cellSize.size;
           break;
-        default:
-          throw ArgumentError(
-            "Unknown type of cell size: ${cellSize.runtimeType}",
-          );
       }
     }
     return TotalSize(weight: totalWeightSize, fixed: totalFixedSize);
@@ -169,7 +165,7 @@ extension GridPadCellSizeExtension on Iterable<GridPadCellSize> {
 }
 
 /// Class describes grid cell size.
-abstract class GridPadCellSize {}
+sealed class GridPadCellSize {}
 
 /// Fixed grid cell size.
 class Fixed implements GridPadCellSize {
@@ -206,12 +202,12 @@ class Weight implements GridPadCellSize {
 extension FixedExtension on Fixed {
   /// Create a list with length [count] of fixed cell sizes with size [size].
   static List<GridPadCellSize> fixedSame(int count, double size) {
-    return List.generate(count, (index) => Fixed(size));
+    return List.generate(count, (index) => size.fx());
   }
 
   /// Create a list of fixed cell sizes with passed fixed [sizes].
   static List<GridPadCellSize> fixedSizes(List<double> sizes) {
-    return sizes.map((size) => Fixed(size)).toList();
+    return sizes.map((size) => size.fx()).toList();
   }
 }
 
@@ -219,11 +215,23 @@ extension WeightExtension on Weight {
   /// Create a list with length [count] of weight cell sizes with
   /// weight size [size].
   static List<GridPadCellSize> weightSame(int count, double size) {
-    return List.generate(count, (index) => Weight(size));
+    return List.generate(count, (index) => size.wt());
   }
 
   /// Create a list of weight cell sizes with passed weight [sizes].
   static List<GridPadCellSize> weightSizes(List<double> sizes) {
-    return sizes.map((size) => Weight(size)).toList();
+    return sizes.map((size) => size.wt()).toList();
+  }
+}
+
+extension CellSizeExtension on num {
+  /// Create [Fixed] cell size.
+  Fixed fx() {
+    return Fixed(toDouble());
+  }
+
+  /// Create [Weight] cell size.
+  Weight wt() {
+    return Weight(toDouble());
   }
 }
diff --git a/lib/grid_pad_widget.dart b/lib/grid_pad_widget.dart
index da66e85..c0f49aa 100644
--- a/lib/grid_pad_widget.dart
+++ b/lib/grid_pad_widget.dart
@@ -70,6 +70,40 @@ class Cell extends ProxyWidget {
   }
 }
 
+extension CellExtension on Widget {
+  /// Wrap the Widget in a Cell
+  Cell cell({
+    Key? key,
+    required int row,
+    required int column,
+    int rowSpan = 1,
+    int columnSpan = 1,
+  }) {
+    return Cell(
+      key: key,
+      row: row,
+      column: column,
+      rowSpan: rowSpan,
+      columnSpan: columnSpan,
+      child: this,
+    );
+  }
+
+  /// Wrap the Widget in a implicit Cell
+  Cell implicitCell({
+    Key? key,
+    int rowSpan = 1,
+    int columnSpan = 1,
+  }) {
+    return Cell.implicit(
+      key: key,
+      rowSpan: rowSpan,
+      columnSpan: columnSpan,
+      child: this,
+    );
+  }
+}
+
 class _CellElement extends ProxyElement {
   _CellElement(super.widget);
 
@@ -161,15 +195,11 @@ class _GridPadDelegate extends MultiChildLayoutDelegate {
   ) {
     final availableWeight = availableSize - totalSize.fixed;
     return cellSizes.map((cellSize) {
-      switch (cellSize.runtimeType) {
-        case Fixed:
-          return (cellSize as Fixed).size;
-        case Weight:
-          return availableWeight * (cellSize as Weight).size / totalSize.weight;
-        default:
-          throw ArgumentError(
-            "Unknown type of cell size: ${cellSize.runtimeType}",
-          );
+      switch (cellSize) {
+        case Fixed():
+          return cellSize.size;
+        case Weight():
+          return availableWeight * cellSize.size / totalSize.weight;
       }
     }).toList();
   }
@@ -193,15 +223,14 @@ class GridPad extends StatelessWidget {
   final PlacementStrategy _placementStrategy;
 
   GridPad({
-    Key? key,
+    super.key,
     required this.gridPadCells,
     required List<Widget> children,
     this.placementPolicy = GridPadPlacementPolicy.defaultPolicy,
-  })  : _placementStrategy = GridPlacementStrategy(
+  }) : _placementStrategy = GridPlacementStrategy(
           gridPadCells,
           placementPolicy,
-        ),
-        super(key: key) {
+        ) {
     for (var contentCell in children) {
       final Cell cell;
       if (contentCell is Cell) {
diff --git a/pubspec.yaml b/pubspec.yaml
index ad79bdd..ba1522d 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,10 +1,10 @@
 name: grid_pad
 description: GridPad Flutter layout
-version: 0.9.0
+version: 1.0.0
 repository: https://github.com/touchlane/gridpad_flutter
 
 environment:
-  sdk: '>=2.18.6 <4.0.0'
+  sdk: '>=3.0.0 <4.0.0'
   flutter: ">=1.17.0"
 
 dependencies:
@@ -15,7 +15,7 @@ dependencies:
 dev_dependencies:
   flutter_test:
     sdk: flutter
-  flutter_lints: ^2.0.0
+  flutter_lints: ^3.0.1
   test: ^1.21.4
 
 flutter:
\ No newline at end of file
diff --git a/test/grid_pad_cells_test.dart b/test/grid_pad_cells_test.dart
index 11b84ec..697bf29 100644
--- a/test/grid_pad_cells_test.dart
+++ b/test/grid_pad_cells_test.dart
@@ -28,12 +28,12 @@ import 'package:grid_pad/grid_pad_cells.dart';
 void main() {
   test('Check equals and hashCode for the same GridPadCells', () {
     final left = GridPadCellsBuilder(rowCount: 2, columnCount: 4)
-        .columnSize(1, const Weight(2))
-        .rowSize(0, const Fixed(24))
+        .columnSize(1, 2.wt())
+        .rowSize(0, 24.fx())
         .build();
     final right = GridPadCellsBuilder(rowCount: 2, columnCount: 4)
-        .columnSize(1, const Weight(2))
-        .rowSize(0, const Fixed(24))
+        .columnSize(1, 2.wt())
+        .rowSize(0, 24.fx())
         .build();
     expect(left.hashCode, right.hashCode);
     expect(left, right);
@@ -52,11 +52,11 @@ void main() {
 
   test('Check internal fields', () {
     final cells = GridPadCellsBuilder(rowCount: 2, columnCount: 4)
-        .rowSize(0, const Weight(3))
-        .rowSize(1, const Fixed(24))
-        .columnSize(0, const Fixed(12))
-        .columnSize(1, const Weight(2))
-        .columnSize(2, const Fixed(10))
+        .rowSize(0, 3.wt())
+        .rowSize(1, 24.fx())
+        .columnSize(0, 12.fx())
+        .columnSize(1, 2.wt())
+        .columnSize(2, 10.fx())
         .build();
     expect(2, cells.rowCount);
     expect(4, cells.columnCount);
@@ -64,13 +64,8 @@ void main() {
     expect(3, cells.rowsTotalSize.weight);
     expect(22, cells.columnsTotalSize.fixed);
     expect(3, cells.columnsTotalSize.weight);
-    expect([const Weight(3), const Fixed(24)], cells.rowSizes);
-    expect([
-      const Fixed(12),
-      const Weight(2),
-      const Fixed(10),
-      const Weight(1),
-    ], cells.columnSizes);
+    expect([3.wt(), 24.fx()], cells.rowSizes);
+    expect([12.fx(), 2.wt(), 10.fx(), 1.wt()], cells.columnSizes);
   });
 
   test('Check constructors of GridPadCells', () {
@@ -87,28 +82,28 @@ void main() {
 
   test('Check GridPadCellsBuilder methods', () {
     final actual = GridPadCellsBuilder(rowCount: 2, columnCount: 3)
-        .rowSize(0, const Fixed(30))
-        .rowSize(1, const Fixed(30))
-        .columnSize(0, const Weight(2))
-        .columnSize(1, const Weight(2))
-        .columnSize(2, const Weight(2))
+        .rowSize(0, 30.fx())
+        .rowSize(1, 30.fx())
+        .columnSize(0, 2.wt())
+        .columnSize(1, 2.wt())
+        .columnSize(2, 2.wt())
         .build();
     final expected = GridPadCellsBuilder(rowCount: 2, columnCount: 3)
-        .rowsSize(const Fixed(30))
-        .columnsSize(const Weight(2))
+        .rowsSize(30.fx())
+        .columnsSize(2.wt())
         .build();
     expect(actual, expected);
   });
 
   test('Check extensions', () {
-    expect([const Fixed(1), const Fixed(1)], FixedExtension.fixedSame(2, 1));
-    expect([const Fixed(1), const Fixed(2)], FixedExtension.fixedSizes([1, 2]));
+    expect([1.fx(), 1.fx()], FixedExtension.fixedSame(2, 1));
+    expect([1.fx(), 2.fx()], FixedExtension.fixedSizes([1, 2]));
     expect(
-      [const Weight(0.5), const Weight(0.5)],
+      [0.5.wt(), 0.5.wt()],
       WeightExtension.weightSame(2, 0.5),
     );
     expect(
-      [const Weight(0.5), const Weight(1.5)],
+      [0.5.wt(), 1.5.wt()],
       WeightExtension.weightSizes([0.5, 1.5]),
     );
   });
@@ -116,30 +111,17 @@ void main() {
   test('Check total size calculation', () {
     expect(
       const TotalSize(weight: 3, fixed: 22),
-      [
-        const Fixed(12),
-        const Weight(2),
-        const Fixed(10),
-        const Weight(1),
-      ].calculateTotalSize(),
+      [12.fx(), 2.wt(), 10.fx(), 1.wt()].calculateTotalSize(),
     );
   });
 
-  test('Check errors. Invalid size options.', () {
-    expect(() {
-      Fixed(0);
-    }, throwsAssertionError);
-    expect(() {
-      Weight(0);
-    }, throwsAssertionError);
-    expect(() {
-      [
-        const Fixed(1),
-        const Weight(2),
-        CustomGriPadCellSize(),
-      ].calculateTotalSize();
-    }, throwsArgumentError);
-  });
-}
+  test(
+    'Check fx() extension',
+    () => {expect(12.5.fx(), 12.5.fx())},
+  );
 
-class CustomGriPadCellSize extends GridPadCellSize {}
+  test(
+    'Check wt() extension',
+    () => {expect(12.5.wt(), 12.5.wt())},
+  );
+}
diff --git a/test/grid_pad_widget_test.dart b/test/grid_pad_widget_test.dart
index b3b368e..f71a35c 100644
--- a/test/grid_pad_widget_test.dart
+++ b/test/grid_pad_widget_test.dart
@@ -66,8 +66,8 @@ void main() {
           columnCount: columnCount,
         ),
         placementPolicy: placementPolicy,
-        children: const [
-          Cell.implicit(rowSpan: 2, columnSpan: 2, child: Text('0:0'))
+        children: [
+          const Text('0:0').implicitCell(rowSpan: 2, columnSpan: 2),
         ],
       ),
     );
@@ -217,7 +217,7 @@ void main() {
 class App extends StatelessWidget {
   final Widget child;
 
-  const App({Key? key, required this.child}) : super(key: key);
+  const App({super.key, required this.child});
 
   @override
   Widget build(BuildContext context) {