In the 70s, trustees from the USDB operated a greenhouse, an auto body repair/painting shop and loaded groceries at the commissary. At the commissary, you got a claim check when you checked out then drove around back where the trustees put your groceries in the trunk. The auto body/paint shop operated on a lottery basis and, as I recall, the customer paid only for materials.
I was an instructor {inmate) there in 73-74. Wayne Reel was the head man. I shared a mail box with Rusty (LT. William} Calley. We did a lot of interesting things there and a great bunch of guys made the time go by quick.