Not sure if it is helpful but the next time you see one of those Nordictrack ski machines for free grab it. The wood skis you stand on are sitting on one way bearings. One on each side of the center flywheel.
Check with your local high school or college. They might have a night time machining class that is available. The high school by me has a class where you can test out on a machine and then are pretty much free to play.
I realize you are probably aiming for a simpler engine but maybe you could watch some videos on Otto slide-valve engines or maybe some on cam stop engines. Little more challenge.
Cool little video I watched lately. Nice vertical side shaft engine at 2:34.
Somewhere I saw a plans that used a syringe (cylinder and piston) it got pushed into an aluminum block that served as the pivot and valve. If you used a bent wire as your crank the only thing that would have to be machined would be flywheel, stand and aluminum block.
Probably had something like this on it.