The $29.99 all-metal desktop Stirling engine kit is one of the simplest. It can be assembled in 15 minutes and is recommended for ages 14 and up. Also for $29.99 is the Exploring Kid Steam Engine Kit.

The Perkins Bronze overhaul kit. The Copper kit for top end overhaul targets the upper areas of the engine, such as the cylinder head and valve train, to address concerns like increasing compression, ...