My goal was to mount my Garmin Varia bike radar on my Thule Tour Rack (which I assume was designed to put a reflector).

Instead of designing a complex model, meant to compensate for angles (the Varia radar must be perfectly vertical), I decided to keep it simple by using a GoPro 3-prong mount instead as a stepping stone. Combined with the Garmin GoPro adapter model from @Brian it made it easy to adjust the angles perfectly, while also making my Thule adapter more universal as it also can be used to mount… well, a GoPro for example :)

I printed mine using Prusament ASA Saphire Blue so that it resists outdoor conditions well.

The holes on the bottom are tightly sized for Ruthex M5 threaded inserts and M5x10 screws. I recommend using Loctite on these screws to avoid that they become loose with vibrations.

For the same reason, I used a Nyloc M5 nut and an M5x20 buttonhead screw on the GoPro prongs to secure the Garming adapter.