I recently purchased some Yubico NFC Security Keys and hated that to keep it on my keyring I needed to hang my keys from a USB port.
This holder clips to the keyring and the security key is held snugly until you want to use it, just push/pull the sides down to expose the bottom of the key and you can pull it the rest of the way out.
It is designed to be printed in TPU. I printed it on my Creality K2 Plus at 100% infill, no brim, no supports and at 0.08mm layer height on a 0.4mm nozzle.
I added some options with different numbers on the side so they can be easily identified.
For the best fit the key should be slid in with the USB connectors facing the printed USB connections on the case/cover/holder (See image from Fusion360).
Video: https://photos.app.goo.gl/ukthoqtp3k6bK4AEA
The author marked this model as their own original creation.