This 3D-printable vintage lens adapter allows users to place optical filters behind the camera lens

It has been designed because large specialty filters are expensive and sometimes don't exist while gel filters are fragile and easy to mount. It supports glass-filters with 1-3mm thickness and a 20-39mm diameter aswell as thin 1.5x1.5 inch filter squares.

Both CAD and 3D-printing files are provided in .step and .3mf format respectively.

Supported lens mounts:

• M42
• Minolta MD
• Konica AR (modified design, not cross-compatible, thus seperate .zip file)
• more will be added

Supported camera mounts:

• Sony E/FE
• Nikon Z [untested]
• Canon RF [untested]

Please read parts list and assembly instructions below.

Required Materials:

• 1x Generic "super slim" M42 to [camera mount] adapter (see linked photo)
• 6x M2.5 heat insert
• 4x Screws: M2.5 x 16mm Torx Flathead
• 2x Screws: M2.5 x 6mm Torx Flathead
• Glue (I used Cyanoacrylate aka. "Superglue" for PLA/PETG)

Required tools:

• 3D printer
• soldering iron (for heat inserts)
• fine screwdriver
• optional: lighter (to clean up the print)

Building the adapter:

1. order the parts you need
2. 3D print the 3 parts of the adapter body required for your camera mount (top, middle, bottom)
3. place top piece with lens-mount facing down
4. melt M2.5 heat inserts into the bottom holes of the top piece (4x total)
5. apply glue to the middle piece
6. line up holes in middle piece with the top and place down
7. line up holes in the bottom piece with the middle and place down
8. use M2.5 x 16mm screws to firmly screw all the parts together (4x total)
9. let glue dry

Notes Adapter:

• flip the bottom part 180° before printing so it doesn't have overhangs
• do a dry fit before applying glue to check if everything lines up
• screw M2.5x16 screws into the heat inserts before glue application to clear stuck filament from the threads
• spread glue with toothpick for even coverage and less squeeze-out

Building the filter holder:

1. Select the right filter holder for you
2. 3D-print holder and holding-plates
3. melt M2.5 heat inserts into the filter holder (2x total)
4. place filters and hold down with M2.5 x 6mm screw (2x total)

Notes Filter Holder:

• the naming convention is "Holder - [diameter]x[thickness] filter.3mf, refering to the glass filters size
• all filter holders are made for 1.5x1.5 inch filter squares. Only difference is the size of glass filters they can take. If you have no glass filters just print 36x1 filter holder for good mix of rigidity and vignetting-resistance
• it's explicitly designed to take both filter types at the same time so you can create filter stacks
• I encourage making more than one filter holder since it's far easier to change them out than to change the individual filters

Printing Tips:

• I just used PLA and PETG. Both worked mostly fine. Sturdier filaments should offer more peace of mind but are harder to print
• one PLA prototype made on a printer with underextrusion issues broke at the bottom plate interface between the screw-thread and flat surface. It has been reinforced significantly but beware, it's a stress point
• all final pre-release prints were done in "0.12mm High Quality" preset on a Bambu Labs A1 Mini

You are free to use, re-upload, modify and make commercial use of this project and any derivative works you create based on in accordance with the simple and permissive licensing terms granted by CC BY license. Feedback is very welcome.

The specific type of adapter plate this is all designed for: https://i.ebayimg.com/images/g/y7oAAOSwjWlhC49V/s-l1600.jpg

Edit 23.07.2025: Fixed filter holder issue where sharp corners get stuck. Now rounded.

Edit 24.07.2025: Fixed glass filter diameter, added tollerance for printing