Designed to hold 4-6 cards and a small amount of cash. This is a very small and compact minimalist wallet. I designed a wallet with intentions to sell it on kickstarter and went through many versions on my 3D printer to come up with an optimal design. This isn't an exact copy of my final version, since those are made from metal, but this does incorporate all the lessons learned and functionality. If you are a fan of the wallet, like the Facebook page and get info about a soon to be launched Kickstarter. https://www.facebook.com/CardCageWallets PRINTED VS RUBBER BUMPER: This wallet works best with a rubber bumper to hold the cards in by their edge. This retainer feature can bee seen in the last picture as the red piece. In the regular version this is part of the 3D print, in the rubber bumper version a hole is left in the 3D print and that is filled with 3/32 (.094) rubber cord stock. OVERSIVE VS REGULAR: My printer tend to run parts just a hair undersized. So the main file is nominal and the oversize has the width and height increased by .020". PRINT INSTRUCTIONS: I think you are probably going to want support material for the small overhangs and connecting rail. I print it with the money clip side down on the print bed, and prefer ABS for strength. INSTRUCTIONS FOR LOADING THE WALLET: I load my wallet with the back cards (closet to money clip) first and work my way forward. Then I put the money in last. ABOUT THE RUBBER BUMPER: For a long time I just cut up O-rings and used that for the retainer, 3/32 is a pretty common size and should be available at the hardware store. Alternatively you could order 9407K11 from McMaster Carr. 3 feet is the shortest length they sell, it will only set you back about $1, but it will cost $5-10 to ship, so throw in some other stuff on your order. McMaster Carr is a pretty amazing place, so I am sure you can find something you want. To insert the rubber I just cut a point into the rubber with diagonal cutters, fish the trimmed rubber through the hole and then pull the full diameter through and trim if flush. You want the rubber to be a pretty snug fit in the hole. I have also created an instructable to go with this if you want more details and pictures: http://www.instructables.com/id/Minimalist-wallet-with-money-clip/