It is possible to turn heat (or cold) into usable energy by using a Stirling engine. Invented by Reverend Dr. Robert Stirling and patented by him in 1816, the Stirling engine is rarely used these days for the generation of power or to do any real work, but it is often used as a model or even as a toy. However, that does not mean that the Stirling engine is not still useful, as we constantly see new ideas of how to use the Stirling to generate power from waste heat. Our Instructable of the day today focuses on this unique engine, and shows you how to make one for yourself using materials which are easily found and not too expensive. If you make one of these and figure out a way to take over the world, we want some credit.