Consider the Dangerous Book for Boys, a national bestseller, which collected accounts of how play used to be. Unfortunately it left out the good parts: experiments so bold that you would need a Crash Test Dummy to try them. No problem. Construct Crash Test Dummies to test traps, gliders, cannons, and catapults...all adapted carefully from the Boy Mechanic, an early 20th Century treasury of experiments, dangerous in its confidence in the common sense of curiosity. Batteries, rocket engines included.