The use of radio frequency identification or RFID chips is on the rise in technological items intended for personal use. Public transit cards, ID badges for some buildings, even credit cards now contain these tiny devices, some not much bigger than a grain of rice. RFID chips may some day be inserted into passports to speed processing at border security locations. However, they do concern some users because they are constantly broadcasting, meaning someone with an RFID reader could copy and possibly steal some information. You can shield your RFID chips with a device you can build at home.
Cut a sheet of tinfoil at least 17 inches by seven inches, and fold it in half to create an eight and a half inches by seven inches sheet of tinfoil. This will be the bulk of the shield.
Make a solid sheet of duct tape by overlapping seven-inch strips of duct tape with at least one-half to one-quarter inch overlaps, so they create an eight and a half-inch sheet of duct tape.
Place the tinfoil shield onto the center of the adhesive side of the duct tape sheet. Fold this entire sheet in half.
Tape the short sides to create a pocket; this is where you will store your RFID-enabled cards. Fold the pocket in half to make it more wallet-shaped.
Add a top flap to block RFID signals from the top of the wallet. Begin with a double-thick strip of tinfoil measuring four and a half inches wide by at least two inches long. Place a few strips of duct tape on the back. Make this flap the same length, but at least an inch wider than the tinfoil. Place this a half-inch down on the back of the wallet-pocket, so you can fold it over the mouth of the RFID shield when shut.