The Hollow Flashlight by 15-year-old Ann Makosinski is such an awesome and useful gadget, I’m surprised that no one else thought of it earlier. You know how, when there’s an emergency, there’s often a shortage of flashlights or batteries? Hand-cranked flashlights can be useful in such situations, since they’ll need manpower to run.
Turning that crank to power up the flashlight can get tiring after a while though. This is where Ann’s Hollow Flashlight comes in. It wasn’t named that way for nothing, since its handle really is hollow. The base of the flashlight is composed of Peltier tiles, which produce electricity when one side is heated while the other is cooled. In this case, the heat source is its user’s hand, while the cool side is the air in the hollow handle.