UPDATE (v2): I made a minor update to the shape of the slots to help keep the O-rings in place. In the first iteration, I found that they would sometimes slip off.

This is a remix of Guv's original Basic Wallet, which I can no longer find.

The original Basic Wallet was, I think, very well designed and was one of my first prints. After a year of using it, a couple of areas for improvements became evident:

• The plates were bending - raised lettering on credit cards caused the middle to bulge slightly
• The band slots would eventually cause the O-rings to snap - sharp edges and a wedge shape concentrated the strain, causing the bands to break after 8-10 weeks of use.

To address those, I've slightly remixed Guv's original to make the plates slightly thicker and used a rounded slot and rounded the outer edges of the plates to minimize strain on the O-rings. I continued the rounded edges around the entire piece to make it more pleasant to hold in your hand.

I've been using 1/16" O-rings from the plumbing section of any hardware store. I find 3/8" OD x 1/4" ID to be much too small unless you only carry 1 or 2 cards. My preference has been to use either 7/16" OD x 5/16" ID (#206) or 1/2" OD x 3/8" ID (#207) for 5+ cards.

Also check out ThePartGuy's variation of Guv's original at: http://www.thingiverse.com/thing:1234836