On Tuesday, September 1, 2015 at 8:59:50 AM UTC-7, Tom Gardner wrote:
See ads for wallets that prevent skimming credit cards? Are those
considered Faraday cages?

It's easier than that. A credit-card sized chunk of brass or SS shim stock
in close proximity to the card (next to it) will greatly attenuate any interrogation
RF and load the 'antenna' so it doesn't respond. I just keep a business
card from an electrochemical machining outfit in the wallet next
to the RF-responding cards.

Or, there are metal-case 'wallets', if you can tolerate extra silliness.