Rechargeable led flashlight powered by magnets housed in the obligatory mints container.
Step 1: Parts
150 ft. 30 gauge enamel-coated magnet wire
4 1/8" rare earth magnets
4 rectifier diodes (IN4007 MIC)
Resistor (22 ohm)
Some sort of small rechargeable batteries
2 plastic washers or doodads