Yeah I have a box of bent spanners and screwdrivers for odd jobs.
You can make one of these with a piece of broken ring gear as well.

I have to say, minimum of a grinder and flux core mig welder and you are in the door, but what has really changed my life is multiple grinders and drills so I'm not constantly swapping disks or spotwelds drills, a horizontal band saw makes cutting somewhat accurately a snooze, and a pillar drill because I can't drill a straight hole without.
Most of that's picked up pretty cheap and of course not all at once.

To remove crank bolts on a minor at least you can simply attach a long breaker bar and wedge it against the ground and hit the starter for a second. Will loosen right off