I am interested in creating physical coins as I actually currently have a brick and mortar based crypto exchange, I want to sell these locally  however I need to figure out how to create my own, It looks as if all coins created in the past are no longer made but they all seem to have used a shortened private key, was this anything to do on the bitcoin network or simply a 5/6 digit identifier that then associated it's self to the real private key on their website only?