My take on a folding keychain remixed from Evaken's Swiss Army Key Holder. Main changes I made was making the holder a few millimetres longer as my keys would occasionally collide, made the chain holder hole wider to look more aesthetically pleasing. Also increased the recess to make it easier to select keys.

I used m3 nylon nuts and bolts and just cut the excess with a craft knife.

Fusion 360 file included so you can make your own modifications.