At Video Games parlor or many other outlets I see people dispensing Plastic token. These token can be inserted into a machine which does a specific functionality. How are the plastic token verified. What sensor can do that? How do we build such a system? Can there be a paper token system also? How does a currency detector works?
Actually I want to design a system by which a paper token can be created and inserted into a device (not sure which one) but it would tell a detail of the paper token - say I have 3 paper token - pink, red, blue color or I am not sure what other way I can do that - if I insert the same in a device, it would tell me what had been inserted. Think of these paper token as cash dispense request of specific amounts.
What way I can design such a system without doing any online verification?