He uses Kevlar-Nomex for the fabric, but that’s just because it’s strong, not because it’s a good electromagnetic shield. The shielding comes from adding a layer of silver epoxy to the lining, which in turn also reinforces the material. He recommends using regular epoxy with a tin foil layer if you’re looking for a cheaper alternative. If you’re not into making yourself a duct-tape wallet to keep RFID hackers at bay, this will certainly accomplish the same ends. Find the whole guide over at Embedded Edge.