I’d go more with skills rather than a particular job. Teaching an inmate to weld would open up a huge area - everything from ornamental railings to heavy industrial fixtures. Likewise good woodworking skills would have a wide range of applications.
Quick story on the lighter side…
The guy I keep company with, Dave, used to work as a welder where I work building school furniture. In the time honoured tradition of sticking it to the new kid, he and his buddy Mario got one fresh-out-of-school guy, but good.
They’re a pretty skeevy looking pair. Dave’s just past fifty and Mario’s around sixty and they both look a little, uh, used. Anyway, this kid, Darcy, was of the gullible sort. About a week after he started, they went up to him and asked if he could drive. He wouldn’t need a license, just the ability.
Um, yeah he could. Why?
Well, it seems that they had learned to weld in prison together and back in the day the province had a contract with the prison to make furniture for schools and when they got out the factory had gone privatized and so they stayed on. Heh. Complete BS, of course. Anyway, there was this bank they had their eye on…could he meet then about two am?
Well, the poor kid was sweating bullets. If he turned them down, knowing now about the planned heist, what would they do? If he went along, he’d be in a bank robbery!
Now when I say gullible, keep in mind they’d already got him once before. Another fellow started on the same day and promptly quit. Dave managed to convince Darcy that the guy got fired for spitting on the floor. He also had him believing that the welders had to buy their own gas and wire, both of which items he was let off the hook about by the end of the day. He should have smelled a rat - no, a couple of rats - right away.
They did confess pretty quick and Darcy stayed on for several months but I think that somewhere in the back of his mind remained the question…
Just where did those guys learn to weld?!