I managed to cut down the bulk in my wallet by 3 cards by photocopying the barcode side of my loyalty cards and sticky taping them to other cards which don't need to be swiped (nfc based transport card, nfc based car share card)
Ooooh....this low-tech idea is very good. I've often wanted to create a single card (same shape and size of credit card) that I could print my essentials on so they could be scanned by a red laser scanner.
