Do Prisoners Really Make License Plates? As a child my parents would always tell me that if I didn't behave as a child, I'd end up having a life in prison making license plates. I only half believed them. I wondered if prisoners actually ever made the license plates we put on our cars. I found out the answer... About 80% of license plates in the United States ARE made in about eight prisons. Some of those prisons actually make plates for more than one state. 3M manufactures the plastic sheeting that goes on the plate, the actual metal plates are stamped in prisons, and then the sheeting is applied.