A cover for the quick release on the wheelbase side, just to help ensure the electronic contacts don't get bumped, damaged, or gunked up if you don't keep a wheel attached. As a bonus, it should fit over any holder you have that slots into the wheel-side quick release so you don't have to have it lying around when not in use!

It fits slightly loose on my R12 wheelbase (40mm diameter/20mm depth) with the cutout on the model at 42mm, so could maybe be slightly reduced in size. Not tested with any other wheelbase.

Shouldn't need any supports to print in my experience.