If you ever wanted to turn the heat from your cup of tea or coffee into piston power, I have just the gadget for you. It’s a Low Temperature Differential Stirling engine model. Invented by Robert Stirling back in 1816, this engine produces power from temperature differences. You can place it on top of something warm or cold like a cup of tea, cup of ice, the hood of your car, computer, etc and it will spin. If you’re in to Steampunk type gizmos, this would be a fun addition to a collection, that will actually work. You can find complete models and kits on Amazon at different prices ranges, or if you’d rather go completely DIY, check out this how-to article from MAKE magazine.