Needed one for the gazebo/grill area so whipped it out quick, came out more elegant than expected. Includes pattern to cut out a "floor" for the ash pit from a sheet of metal, to protect the plastic from burning. Notches measured to fit regular cigarettes in such a way you can push the cigarette in, to keep it gripped so it won't be taken away by wind.

Instead of the metal insert you can use high-temperature spray paint; not tested but allegedly works OK on 3D-printed ashtrays.

parametric FreeCAD project included,if you want a different size and depth; this one is fairly large.

Tested for three evenings by now, works as intended.

Regarding the intended outdoor use - I fully expect the PLA to degrade in outdoor use within a couple years, at which point I'll just print another, and hopefully reuse the metal insert.