Great idea. The credit card payment/verification thing might work well too (although I've been in two bars and a restaurant with a cigarette vending machine lately - no problems).
I use an unmonitored range for most of my shooting and, from experience, the vending machine should also offer targets and small rolls of duct tape
I use an unmonitored range for most of my shooting and, from experience, the vending machine should also offer targets and small rolls of duct tape