I was tired of having to carry the key card for my Tesla Model 3 while surfing. Therefore I created this mini keyhanger instead.
I dissolved the Tesla Key Card in acetone and took out the chip and antenna.
Twist the antenna to form an "8" and fold in half. Repeat and you will end up with a spool fitting the keychain.

Remember to test the chip and antenna numerous times during the process on your vehicle to make sure the key still works.

I filled the gaps and glued it all together with Tec7 sealant to make it sort of waterproof. Time will tell how it holds up.