A few photos of the second version of my 3D printed cootie key.
This version has two bolts securing the end of the strap to avoid up/down rotation around the fixed end. The finger pieces are a little larger, and have a pin+recess which pass through a second hole, securing them to the strap so that they cannot rotate. The strap in these keys is made from 0.032″ brass — it is less prone to “twanging” and provides a very reliable contact. All of the hardware is brass, #8-32 and #4-40.
I also built one in black.
These keys are very light weight, and need to be held or secured to a heavy base for desk use. I use double-sided foam tape to attach the keys to granite countertop samples I got from a local supplier. A piece of run anti-skid mat on the bottom of the base makes a very stable desktop key that stays put.
The original design only had a single bolt securing the end of the strap, and a single screw holding the fingerpieces. It works well, but parts are prone to movement around the bolts.
I have published the original version on Thingiverse, you can find the design here: