Many people, like myself, now have ORCA cards issued by their employer in addition to the personal card they own. I carry both of them in my wallet. The problem is I can’t tap my wallet on the reader with two cards. The reader tells me “one card at a time please” and prevents double-charging, which is a good thing but it requires me to take the card out to tap. My solution to this is to wrap my personal card in aluminum foil, then keep the card separated from the other ORCA card with the other cards in my wallet. The first time I did this was with 10 layers of foil but I tried with just a single layer and it works. The metallic foil effectively shields the card from radio waves and prevents it from being read. The other cards keep the foil far enough from the card you want to be readable. This means only the side of the wallet that the unwrapped card is on can be read.
I’m aware that there are similar products for passports, enhanced drivers licenses, debit cards and other contactless cards but this is a quick and cheap solution you can do at home. This trick also appeals to people who don’t want strangers ‘sniffing’ their contactless cards for potentially malicious purposes.