RFID, Contactless, NFC or whatever you want to call it, was a game changer when it came to Credit and Debit Card purchasing. This year, Transport for London, who run the underground and buses in the UK capital, launched contactless payment in addition to its 'Oyster' card payment system.
This was really useful, particularly for visitors to the city, but a very real problem appeared; something that TfL termed 'card clash'.
'Shielding' contactless payment cards from your Oyster card/desired payment card protects commuters from paying too much or not paying at all (and being fined). For anyone visiting the fine city of London from abroad, this is a must read, as TfL will refund mistakes caused by 'card clash', but not transaction fees or other costs.
This instructable is entered in the 'Protection' and 'On a Budget' competitions.
Step 1: Step 1: Empty the Wallet
As it says on the tin.... take all the bits and pieces out of your wallet... those receipts, store cards and train tickets do nothing to help your shielding endeavours!
Make sure you note which side of the wallet you keep your Oyster/desired payment card. For this instructable, I normally keep my card on the right hand side. The design can be adapted for either side of a two part, or any segment of a 3
Step 2: Step 2: Measure Shielding Material
Shielding material can be any electrically conducting material with holes much smaller than the wavelength of the tag. For RFID/NFC/Contactless, this is around 20m, so don't worry if there are creases and little holes in the metal!
Copper is the optimal material for shielding. It is used in networking and computing applications for this. For these low power applications, however, aluminium foil is fine.
The shielding material should be the size of the wallet's largest pocket, plus the size of one segment. This allows the card to side to be doubly shielded. When you measure it off the roll, this allows you to fold the material 3 or 4 times. This is fine, and helps if anything.
Step 3: Step 3: Folding
Fold the screening material over, so that it is the internal width of the wallet. The excess should be doubled over in the segment where the desired payment card would sit. Fold the material until it is also the same height of the wallet.
Step 4: Step 4: Insert Into Wallet and Re-fill
Insert the shielding material into the outside pocket of the wallet, with the payment card or oyster card on the outside of the foil i.e. Wallet Material | Card | Foil | other cards and money.
Fill your wallet back up.
Test that the wallet closes, and that all your cards and cash is inside the foil sandwich - except the payment card which should have an unshielded view of the outside surface of the wallet.
Use the wallet, travel safely and save some money too!