This is just something I made for fun. It's a locomotive style reciprocating (1/2 stroke cycle) steam engine. I didn't originally design it to run, just be a model. But after some careful sanding and filing, as well as liberal amounts of graphite, it does run on compressed air. I may modify it at some point. ...Give it a larger piston and larger valve ports.Here's a quick video if you want to see it run (Sorry about the aspect ratio).http://www.youtube.com/watch?v=FfVjyoL2gy8&list=UUKo5IpKOhxv8yhSzxeK-l0g&index=1&feature=plcpI've included the nine (9) parts as STL files. And Also a Rhino model file if anyone wants to modify it.The AirEngineComplete.stl is simply for the image.It should be fairly self explanatory to put together. The shaft on the flywheel is a little bit too long. So unless you plan to use it as a power takeoff you'll probably need to cut it down.As always I'm happy to help answer questions etc.