Desktop stand for the Amazon Echo Dot 3rd Generation I have fiddled together. This is already the second version, but there are still improvements to make. The back wall is a little weak and the base should be 3mm higher. Besides those two minor things it fits and works fine.
The two slots on the bottom are for "hot glue feet", but you can attach some glue-on feet as well, of course.

EDIT: added v3.1 as 3mf with parts and stl (smoothed)
EDIT 2019-07-03: added v3.5 as 3mf with parts, stl (smoothed) stl (smoothed arch) // redesigned AGAIN :D