UGears: are a series of 11 new mechnical models built from wooden pieces that spring to life with the help of rubber band engines, cranks, or with the assistance of gravity. Similar to balsa wood insects, the laser-cut pieces assemble like a puzzle without need for glue or adhesives. The most impressive design is an elaborate 480-piece steam locomotive that’s 12″ long and propels itself up and down a provided track with an internal engine.

http://www.thisiscolossal.com/2015/12/ugears-self-propelled-diy-mechanical-models/