You don't need a CNC to make your own core ID cards. We print from a template, apply it to PVC, then cut it with a ruler. The left/right sides are at an angle so the top is slightly wider than 3" and the bottom is slightly less.
...but then you have to move the damn Core ID cards out of the way first to read thatWe use mostly 3M - has the info printed on the inside of the core.