After seeing Dhani Sutanto mod his Oyster Card (London transit pass) into a ring, I got excited to try something similar with an CharlieCard (Boston’s RFID transit pass). You can dissolve the card in acetone and then remove the RFID antenna and chip inside. Check out our more detailed guide to this process over on our tutorial site. The video below contains the RFID-modding section of our iPhone replacement backs video:
We found that when placed under one of our replacement iPhone backs, the tag didn’t read, so we fiddled with tape and paper until there was enough air space between the metallic bulk of the phone and the RFID antenna.
One post-it note and four layers of packing tape later, the tag scans just fine from within the back of the iPhone, even with 4G and wifi turned on.