What types of crafters could produce them, and what materials would be required? I could see proprietary metal dies to stamp tokens, but it would require a skilled metalworker to strike them. Making the die might require skills in both metalwork and sculpting.
On a related note, what skills and materials should be required to make guild badges. An engraved or cast item would require less than a bejeweled or enameled one for instance.
Yes, I know this will require implementing additional skills. Just throwing it out there.