Summary

This is my version of "a mechanical gizzmo" by JML31347. It didn't look like it would work as is, so I designed my own parts using Autodesk Inventor. Prints out well with no supports, caps snap onto pegs. Fun toy!
Edit: I uploaded an improved version that has a piston that moves instead of the pin, here: http://www.thingiverse.com/thing:694879