The Cypress Wallet by Connor Ferster is an interesting take on the slim wallet by incorporating a better bill/money area that doesn’t require you to peel the wallet apart like most bi-fold wallets. The bills are clearly visible on one end while the other end neatly hides the other half of the bills with a credit card area. All of this is done while keeping the wallet as slim as can be.
Unfortunately, it’s sold out so I can’t get one to check out, but if you like, you can sign up for their mailing list to know when it will become available again.
Or, if you consider yourself crafty, Connor has actually released the Cypress wallet design under a CC Attribution 3.0 licensce, so you can grab the PDF’s here and make your own.