The Ultra low temperature-differential Stirling engine as kit: It takes about 2 to 4 hours to assemble this great little precision engine. The kit includes all the parts and instructions to build the engine. No machining is required. Only common hand tools and epoxy glue are needed to put it together. It's a great pleasure to assemble a real little Stirling motor yourself and watch it running by the heat of your hand, a coffee cup or ice cubes.