BYO Wind Turbine
Construction set with illustrated instructions. Build a model wind turbine - at 50 cm high and with a blade span of 34cm, it's quite big. Wind energy gets converted into light via gearing and generator.
For 8+, but teens and adults will be proud of it too. From the reliable 4M Green Science brand.
Turbine sits on embedded 2litre plastic bottle. You'll need a small crosshead screwdriver.