Stirling engines are wonderful tools to teach science. There are plenty around that start going after you apply a bit of heat. The PeleusTech Hot Air Stirling Engine Tractor looks much more impressive though. It is made with brass, stainless steel or aluminum alloy. Simply bring some 95% alcohol, and you are ready to go.
This tractor measures 10.4 x 5.47 x 4.92 inches. You can find out more here.