Had to mention another Kickstarter project: Supr Slim by Supr Good Co. A really, really thin wallet or as Supr describes it: “a super-thin, card-carrying over-achiever. Designed for minimalists.”.
The two guys behind Supr got fed up with regular thin wallets made out of conventional materials like leather that got out of shape after a while (or was designed for a specific number of cards) so they created the 3 mm thin Supr Slim wallet out of a durable and very elastic material that wraps tightly around your cards. So, cram one, two or ten cards in there and they’ll fit snugly without stretching it out. Also, it’s available in six colors and the material is RFID friendly.
Kickstarter.com: Supr Slim Wallet (about $25)