I took dimensions with a set of calipers, then I sketched up a quick model in cad of the key switch, and then what I wanted in the keychain. Afterwards I decided I wanted to make them out of some white acrylic I had. I then sliced up the keychain model into 1/8" slices in the model and sent the sketch to my university laser cutter. The thickness of the acrylic prevented me in making it snap into place so they had to be glued. The pieces of acrylic were solvent welded together after they were cut and holes were drilled by hand for the chain. I also explain all of this in the video as well.
Thanks for the interest!