How about a hot air paddler. Friend Jim Brassett in the south of France produced this very quick to build model. Powered by a "tin can" hot air engine, the performance is best described as "gentle". It would be much better if only he would cure a leak around the displacer rod where it exits the displacer cylinder!
As you can see, the displacer cylinder is a baked bean can. The displacer is a cut down beer can, and a piece of wardrobe rail is the power cylinder. The power piston is turned from a piece of dural, and the rest is from odd pieces of wood, wire etc.
Malcolm[/i]