Steve wrote
Hari Seldon wrote

people the chance to use their equipment and learn how
to run a mill/lathe/ect, while getting some free work out
of them?

"learn how" costs would only be second to "insurance costs"

True, but one could start on simple stuff or only do one operation
at a time and I'm looking at this as the employer/"teacher" only
dealing with working machinists as "students", not newbies who
have no idea what's going on.

And maybe a way to deal with the insurance issue is for the "student"
to be treated as a contractor, exchanging work done for the employer
for skills learned?