Many of the news articles and videos I've seen promoting this show the trigger area being a cone shape going upwards. This is not the case. The sensor is only triggered when your hand is directly in front of it. Most of the time when you touch your face, you don't bring your hand up perfectly in the center of your body like you have to do to trigger this in it's current form.

The pendant case needs to be angled upwards at about 15 degrees for it to work as described. I would edit the design if the 3D files were provided (not just the STL) ... or I may just make one from scratch that uses a heat set brass threaded insert as well, so that a single screw can hold the case in place. The "snug fit" design isn't very reliable.