I have been making some RF shields for my bank card and passport. There is a lot of stuff on YouTube and elsewhere about DIY aluminum foil wallets, but I find that beer cans are much better for the purpose. They have the right stiffness and hold whatever shape they are bent into, and they are thicker than foil, though I'm not certain by how much. It is easy to make sheaths from them that slip into existing card pockets to block both sides. Yet I am unable to find anything on-line about the efficacy of this material. It seems to be all about foil. 


Has anyone experimented with this? I know foil is not 100% effective unless several layers are used. How does beer can aluminium compare? I am aware, by the way, that no documented case of paywave fraud exists. I also know that the range of the scanners is very limited. I am doing this as a matter of principle and also just because it interests me. 


On a related note, I see that the antenna loop in the passport is much, much bigger than the one in the paywave card. Is there a reason for this? Does it mean the passport carrier can be tracked throughout the airport?