Berlin police find radioactive iodine on playing cards
You can also get cheating devices [1] where the edges of all the cards are printed with IR barcodes, then a special camera (concealed in a modified phone or car key fob) can tell you upcoming cards by looking at the edge of the deck.Of course, you need to convince people to play with your deck of cards first, so you can't just walk into a casino with these things.[1] https://www.elie.net/blog/security/fuller-house-exposing-hig...