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.