My RV has a 6 inch OD rear round PVC “bumper” and hose storage. This helps me use it for storing and securing small items on top of it. They can also be used to mount a 5 inch OD PVC pipe. Includes FreeCad .Fcstd file.

I printed in PETG on a Prusa XL using 15 Gyroid Infill and 4+ layer vertical walls and no supports. Working well so far.