1/12/2018: Added a "large version, a little thicker, and able to hold a bill folded in half, rather than in thirds.

This is a simple, one-compartment wallet. It's just big enough to hold a credit card or two, your license, a couple business cards and a small amount of cash. It's small enough that it fits very easily into your back (or front) pocket.
I made this using PCTPE nylon. It gives it just the right amount of flexibility so that the top and bottom snap nicely together, and it's tough has hell.
After having to endure a pat-down at the airport because my license picture was unrecognizable, I felt I needed something that would protect it against the grit and dirt that seems to make its way into my pocket, and I didn't want a full-size wallet. This fits the "bill" very nicely.
I added my name as raised lettering on the inside. Of course I left that off of this version, but I've included the Sketchup (version 8) in case you want to add that or any other feature. Since Sketchup gets a little, well, sketchy when doing curves on small dimensions, the units are in meters instead of millimeters (scall x1000). So export to STL as meters.
The two halves naturally snap together, no hinge - just press the base of your thumb against it and pop it open. Not sure yet if it's water-tight, so no guarantees :)