You don't have to be a genius to create these ingenious contraptions, you just need rubber bands, glue, some common hardware and tools, and this illustrated project book for builders 10 to adult. Discover unexpected ways to turn common materials into 19 crafty contraptions that might be surprisingly simple or curiously complex. Step by step photos show how to create slingshot rockets, unconventional catapults, and even hydraulic-powered machines, all while learning key engineering principles.