After getting inspired by the Helicopter ( http://www.thingiverse.com/thing:5225 ) that I printed the other day I thought it'd be fun to design a rubber band powered boat. It's still printing so I haven't seen the final results yet.

I've finished up the first printing of the boat and there are some issues. I was hoping to use dental rubber bands to provide power to the propeller but the notch in the propeller is too small to hold the band. I think I'll have to revisit the design to get the boat powered. But on the other hand as a boat to just float in the sink it works just fine. Depending on the resolution of your 3D printer you might have to open up the steering hole or the hole in the hull to fit the wheel or the propeller.