Has any one or their friend ever built a steam engine from junk parts?
Answers:
You do need a source for steam, a cylinder with opening at both ends for the steam and a piston to drive the flywheel. However, first and foremost you need to think safety. There is nothing worse than a steam burn. I would not build one, but you may be able to buy a small working model. Maybe a jet of steam driving a pelton wheel would be a much simpler design to drive your dynamo.
Other answers:
no
no
No, but I do enjoy working with steam engines. I don't know of any "junk" ones around, but you may be able to find one on e-bay. You'll need a boiler though, and several other things. It's probably not a good idea unless you have a lot of extra time and money, as well as a hobby boiler license.