I've been carrying around a USB flash drive on my key chain to hold all that geeky stuff I need, but I decided that was totally 2006! Now that they have those SD cards that also have the USB interface I thought I could lose some of the stuff on my key chain, and just hold one of those in my wallet. The following is an example of how that could be done, as well as pretty simple instructions(I think).
Step 1: The supplies...
model SD CARD
Fake credit card
I get a few fake credit cards in things a week, so there isn't a whole lot of stress involved if/when I make a bad cut.
Step 2: Do some tracing...
Pretty simple, just trace the SD onto the paper.
Step 3: Get to cutting
Also pretty simple, I used a straight edge and cut on the inside of the line I had previously drawn. That way the fit would be snug.
After a quick bit of usage testing I put some masking tape on the end of the card so that I could pull it out easily.