We put together a snap-together prosthetic hand that's designed to move, and started trying to understand the mechanisms inside and how they work. The hand can be downloaded from http://www.thingiverse.com/thing:92937 .

We're printing 5 new fingers, each with a slot fitted for our pen attachment (or some other) and a new bridge to get rid of all the hot glue. We've removed the front part of the fingers and the rear bridge so we'll be able to add them in when they're finished.