On 20/05/2013 14:38, therustyone wrote:
On Monday, May 20, 2013 2:22:00 PM UTC+1, Lee wrote:
Can always re-purpose the tin foil from the hat to screen the card

You would need a ferrite-based card holder to deny magnetic field access.
Could be a business opportunity.

Here's one company that has been offering products for several years. I
expect there are others.

http://difrwear.com/

Bernie