[kens]

Having looked at a few RFID cards, there are a couple of problems. First, the dies are very, very small (the size of a grain of slat) so they are hard to manipulate and easy to lose. Second, the die is glued onto the antenna with gunk that obstructs most of the die. You can burn it off or dissolve it with sulfuric acid, but I haven't had success with more pleasant solvents.