I'm surprised there do not seem to be any cases for Trackr devices on Thingiverse yet. I just got a bunch of them for family and friends and decided that I'd like a little extra protection for them (and I just started 2-color printing and thought this would be a fun thing to design).

There are two parts to print out: top and bottom. The uploaded STLs are for the plain pieces. Once printed and cleaned up, you simply press the two together around a Trackr Bravo device. You can still use the keyring that came with the Trackr, and I would recommend putting the ring on first. For me, the top and bottom fit extraordinarily well together with simple friction (I gave 0.2mm gap between fitted faces) so I did not design a catch or anything to keep them together (YMMV).

The SketchUp file is included for anyone wishing to customize. The original top and bottom are labeled along with the design and intermediate steps of combining the design with the top to form the new pieces needed for 2-color printing with Cura. Cura needs the bottom piece as one file and separate files for each of the two colors for the top part. One can then pick the source material for each component and then merge the two for printing.