What it would be
A card sized to a lanyard, carrying the wearer's name, their shop, and a code that resolves to their verified Worldwatch profile.
A fair floor is the one place in the trade where strangers do business at speed, and the usual answer to who someone is comes down to whether the other party recognises the shop name. A tag that can be checked is a small improvement on that, and it costs nothing to print.
What has to be settled first
The same three questions as the business card: approved mark, resolvable profile URL, and whether Worldwatch supplies the file or the printing. A tag also has to survive being printed on a home printer, which constrains the design more than a card does.
The kit overview lists the rest. Contact reaches the people deciding it.