ThinkFun Paddle Wheel

This is based on the large wheel from the ThinkFun construction set, in fact the only difference is that this one has 8 slots where card or plastic can be inserted (see pics).

You could use one wheel to create a paddle, a water wheel or wind power a project. If you prefer to use larger bits of card you could also use two wheels in combination (see pics).

If you want to use the project in water (either as propulsion or to harness water as a power source) you could use plastic (e.g. strips