This is a simple mask/diffuser for a 8x8 WS2182B LED matrix. Why use acrylic as the diffuser when you can use white PLA? The first layer is super important here, so make sure your filament is dry and your build plate is clean. It doesn't need to be perfect, but some bigger defects will show through the LEDs

Couldn't get a great picture of it in use with the LEDs because my phone's camera sucks, but I think you get the idea. It looks much better when human eyes are looking at it!

This isn't for the Adafruit 8x8 matrix, this is for the generic WS2812B modules you can get from Aliexpress. The separators that go over the resistors on the module are recessed so that the diffuser will sit right on top of the PCB.