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.

You can put a lot of different engines in the STR, but an Alfa Romeo V6 is a common option. Combined with the car's light ...

It shouldn’t come as much of a surprise, then, that you can also still buy and build the Visible V8 model engine kit, first sold by Renwal in 1958 and one of the longest-selling plastic model ...