Build the ROKR M870 shotgun, a 170-piece wooden puzzle replica of the Terminator-style pump-action with a working rubber band firing mechanism. Pump the forend to load, pull the trigger to release. A desk-scale model where the action cycles cleanly enough to fire across a room.
 
The build
The pump action is the part that sets this kit apart. Slide the forend back and the internal sear engages a rubber band; pull the trigger and it releases with a sharp snap. The ROKR M870 shotgun assembles from 170 laser-cut wooden parts in about an hour, and the fit is deliberately tight — pieces seat with friction, no glue, no slack. Once the receiver closes around the trigger group, the whole mechanism cycles like a real pump-action.