In chapter 14 of
Model Making there's plans for a light steam engine and boiler. The author suggests using the combination to power a model airplane. I have a slightly more mundane in use in mind, I want to power an old push mower I have with the thing. However, the plans aren't very detailed, with components unlabeled, and some dimensions missing. It is, however, the only set of plans for a 2 HP steam engine that I've found that I won't have to buy any materials for, having enough scrap laying around for 99% of it. (It also appears to be a
lot lighter than any of the others I've seen, which all seem to weigh around 50 lbs or so.)
I'm planning on making a mock up out of cardboard and the like before I cut metal so I can hopefully figure out all the kinks ahead of time, but I thought I'd ask before I started work to see if anyone had any pointers.