Great idea. I have a "hookup" for metal and plastic tokens like these that would cost less than a dollar each, much cheaper when you get over 100, and could lay out the money to make them for you if you want. You could serial number them and even QR code them to track their history. Love the idea let me know if you wanted to create a more durable limited run of metal or plastic coins. In the USMC we have "challenge coins". They would be very similar to those