Radio frequency identification (RFID) tags placed onto identification and bankcards contain data that's read into a computer system by RFID scanners. The scanners can read this data from a distance of several feet, and this can lead to privacy concerns when cards are scanned without the owner's knowledge or consent. It's possible to block scanners from reading your cards if you place cards within an RFID shield. Since the shield merely consists of a piece of blocking metal between the card and the device, you can employ a DIY solution with a modified piece of aluminium foil as the shield's body.
Place a sheet of aluminium foil onto a flat surface. Measure the item that you need to shield. Add an extra inch to both the length and width of the measurement, and then mark the size of the RFID shield you wish to create onto the foil with a marker. Cut the foil along the marked line using a utility knife guided by a straightedge.
Cover the foil with strips of duct tape. Place the tape in straight rows, overlapping along the edges of each row by 1/4 inch until you've covered the entire sheet of foil. Flip the foil so that the duct tape faces downward, and the foil is visible. Apply a layer of duct tape over this side of the foil as well, to prevent tearing when the card is placed within the shield. Trim a 1-inch strip from the length and width of the covered foil sheet to match your object measurement.
Create a second duct tape covered sheet of foil cut the same size as the first.
Place one foil sheet atop the other with the edges aligned precisely. Create a pouch using the two sheets by sealing the seams three of the four sides with the duct tape.
Use the shield by placing your items containing an RFID tag into the pouch, covering the item completely within the two foil sides.