Leather had a good run, i've had the compact saddleback wallet, but nylon has won the game.

Being a sailor, I am well-acquainted to the strengths of nylon and if you think about it, there are few better choices for a durable material to stitch together for this purpose. It's tough, light, shows no wear, and obviously waterproof. It won't seep dye onto your cards like leather sometimes does.

It holds six cards and my car key taped to a card, with a decent amount of cash. I thought a minimalist wallet would have minimalist capacity, not so. Nylon is slippery, which means it comes out of the pocket easily, but it would also be easy to hold it upside down and shake all the cards out of it. Not an issue, but notable.

1 Year update - The wallet has a loose thread about 9mm long, that's all the wear it shows. It stays pretty clean for how dirty i am. Now it holds 10 plastic cards, 4 paper cards, 9 paper bills, a hidden razor blade and a car key with the plastic melted off of it. I find it's less likely to have cards slip out of it if you jam it full.