Handing a player the card their character carries does something a character sheet cannot: it makes the name on it somebody a guard can refuse.
86 × 54 mm is the size of every real card in your wallet, so a printed one behaves like the thing it imitates — it fits a sleeve, a pocket and a card holder. On it: the issuer, a photograph, the name, four particulars of your choosing, a serial, a stamp and a signature.
A 1920s licence, an Eastern Bloc pass, a cyberpunk corporate badge, a free city’s letter of safe passage signed by the council’s clerk, a present-day federal service ID with a hologram strip. Export it flat or with 2 mm of bleed, at 300 DPI; on 250 g card it survives a whole campaign. The ticket that got the holder through the barrier is a Ticket, and the report filed when the card turned out to be forged is an Official Form.