The best way I know of handling such a situation is to join a model making club (model engineering, model live steam, model ships, etc.) in your area, and get to know the better knowledgable members well.
Then for the services a member provides for you, you offer something of value in return (free legal, dental, medical, sevices etc. are always welcome)!
That's how I do it, but not just restricted to the list above, which is a little, but only a little, tongue-in-cheek. Eg. offer to buy a nice-to-have tool which could otherwise not be justified.
Under NO circumstances would I allow anyone to operate my machinery, for the very good reasons given by others here. A band saw or drill press might be an exeption.
The only alternative I can think of is to take machine shop classes at your community college. Once you have learned the basics of machine tool operation you can talk to the professor and he would cut you some slack to make your own stuff........I certainly would have.
But, without good and demonstrable machining skills it is highly unlikely that you will get to use privately owned machines.
Trust this helps.
Wolfgang