The foot from the bottom of my keyboard went missing one day and my heart was broken. The other foot tried to console me; letting me use it as a reference to make another one. I didn't want another, I wanted the original! The other foot persisted and passed me a straight ruler. We looked at each other and laughed. I just guessed at other measurements...didn't want to waste too much of its time. In the end, the replacement piece gets the job done and is easy to print. On a side note, I found the old foot the other day. Haven't put it on yet, this replacement piece works just fine and doesn't resent me like some other pieces of plastic.
While not a very complex mechanism, this design provides the desired springiness and snap when opening/closing the foot that is found in the original. There's no spring, but it wants to be either open or closed. Neat!
edit: oh, yeah...it's a for a Logitech K120 keyboard.