Assembling video -> https://youtu.be/7Syfghqs-z8
I started with the original model -- https://www.thingiverse.com/thing:2986418. And printed both case for RGB LED strip and a diffuser. Since I don't have a Clear PLA I printed it White -- so the diffuser came out too thick (0.6mm) and trapped all the light
That's why I decided to reduce the height of the diffuser to 0.2mm (I did it in FreeCAD, both .FCStd and .FCStd1 are uploaded)
Make sure the "Initial Layer Height" is set to 0.1mm!
Black and White