This is a case for the Fido U2F Plug-Up Security Key. I was concerned about my Security Key getting damaged on my keyring, so I created this case to go around it. This is designed to print in one pass of a 0.4mm nozzle and allow a small amount of shrinkage of the plastic. I also drilled the hole a bit larger on the Security Key itself so that it would fit on my keyring. I use a bit of paracord for my keyring.