Review on Minimalist Aluminum Organizers for Men's Accessories: Automatic Wallets, Card Cases & Money Organizers by Lungogo by Damon Atonyo

Works great as a cardholder. I would keep it in a different bag than your phone as the edges are still pretty hard and could scratch it. The inside is lined with felt to keep the cards from falling out. Map placement can be a bit inconsistent depending on how many maps you have loaded. If you only have 2-3 cards, you can push a little further than usual.