I couldn't find an R2D2 Echo mount that I liked, so I mixed a few together, modded a few parts, and designed a few parts of my own that were missing (none of them had vents).
This is for a 3rd Gen Echo with a 99mm diameter.
Please excuse the color scheme. I made mine into a C2-B5 because we have a black echo.
These were the different designs incorporated:
https://www.thingiverse.com/thing:4364414
https://www.thingiverse.com/thing:4354796
https://www.thingiverse.com/thing:3542205