I had posted here about it when I did the conversion initially, but Jen asked me to take it down until she had a chance to test it out. This was well before lockdown, but she hadn’t had a chance to actually get it installed until recently. The Magic Band puck form factor can be cracked open and inside there is an active RF board with coin cell, but also on the board is a DESFire EV1 and antenna, totally separate from the active stuff, but just parasitically sitting on the same PCB. I removed the DFEV1 and made it into a flexDF for her.
You cannot take a flexDF to the park and make it work because even though the DESFire EV1 is a multi-application chip, nobody shares that capability with anyone else. This is explained about midway down in this post after the big “important” sign.
Since the article is out now, here are the photos from the conversion…
This is the PCB inside the Magic puck. You can see where the MOB packaged DESFire EV1 was on the board and the antenna leads going to the “wings”. I desoldered it from the board.
This related article has these images as well - My Attempt to Become a Disney Cyborg — Update | TouringPlans.com Blog