Link: Evil Mad Scientist Laboratories - Inside the PayPass: Credit card case mods.
The PayPass is an RFID version of the MasterCard credit card.
It is often available as a keychain "fob," like the one shown above.This particular one is from Citibank and is– as far as I can tell– a free optional addition to any Citibank Mastercard account. These have been in the wild for about a year now, and seem pretty handy. The obvious downside is that the RFID readers are far from ubiquitous. Still, things are improving and there are now quite literally dozens of places where you can use them.
From a hardware perspective it's easy to see that this fob consists of the RFID element itself encased in a big block of plastic. And of course, plastic can be removed.
From the outside of the fob, it's really hard to tell what's on the inside. They've left just a tantalizing blurry window to see that there's a chip in there. So, that's the "before" picture.
The active circuitry inside the RFID keychain is potted into hard plastic, which I'm guessing is polycarbonate. To gently remove the circuitry from the inside, we placed the fob into a steel bowl filled with acetone, and let it sit for 24 hours.
