I’m a big fan of anything mechanical - and I love engines.
Over time I’ve seen a bunch of nice theoretical engines sold on amazon for silly money - 50-60 quid but they come with nice stands.
Anyway the nice Chinese folk now sell a sterling engine for £11! it comes with a crappy stand but what a bargain!
I myself have ordered one and looking forward to the raw parts to arrive. The plan is to ditch the stand and make my own using the Shapeoko and some beautiful materials I have left over.
they can be found on banggood - I promise it’s not a porn site ;p
Ages ago, there was a science fiction novel where a military robot gets loose and wanders into South America, and one of the things which it does is make a Stirling Engine to generate power for itself.