The bottom is thin; I used 3 layers but next time I will use 2 layers for the bottom in slicer settings. I have an older house. The bathroom light, fan, heater combo is way bigger than it need be. Which means it would leave a nice hole in the ceiling if I tried to replace it with something more modern looking. Plus, the original light cover was yellowed and didn't make the room very bright. So, it got pitched, and we went bare bulbed for a few years. then enter Tinkercad. I think it updates the fixture just enough that it no longer looks like it should have stayed in the 70's. (Maybe the 90's) I suggest using Petg at the least. but with the LED bulbs you might be able to use PLA. I don't know I typically use Elegoo Petg rapid or pro unless I need a special color. Definitely use clear. Like I said the bottom is thin; so, I used 3 layers but next time I will use 2 layers for the bottom in slicer settings. also I did use tree on build plate only for support, don't know if I needed to.