When I lived in California's High Desert in the 80's there were a couple of these businesses around. I don't think they lasted for a couple of reasons. Primarily insurance cost. Secondly, the fact that the people using it didn't treat it like they owned it (i.e. tore hell out of things). They left junk all over the place, didn't clean up etc. I think if it were supervised correctly it could work as a business. First thing is you can't let the customer determine working hours. Also wold need to protect your investment by charging a large deposit.