I've used a ton of different minimalist wallets in the past, but couldn't ever really find one that I loved. After I got my printer, I decided I would design and print my own! This wallet holds 6-8 card, depending on how thick the cards are. It doesn't have a dedicated spot for cash, but I just slide the cash in with the cards when I have it. I have printed this with both PLA and TPU. I have found that printing in TPU allows the cards to be tighter, while easier to pull slide out. With the harder PLA, you have to have exactly the right amount/thickness of cards or else they could fall out. The one I currently use is TPU and it's amazing.
I experimented with regular supports and tree supports, but in the end just used the regular supports for the notch at the bottom and the hole in the middle. I also printed with a brim.