I have two particular ceiling lights that I wanted to partially block from shining directly into my eyes while watching TV.
I don't know how common this size and particular shape are, but It's modeled with a 5.8in (147mm) diameter and has a 10 degree slope to the ribbed insert, which catches into the matched ribbing of the inset light barrel.
Note that I've uploaded both a .step file as well as the typical .stl. I'm able to get a much smoother curvature in the slicer with the step file, without any of the faceting that comes from the tessellating in the stl.
The author marked this model as their own original creation.