Hey Andrew! Try this: If you make the grid pixels square and drop a sheet of translucent acrylic on top of that, the effect is pretty cool.

Here's a "Game of Life" display I made using this technique: https://digitalhorology.etsy.com/listing/1644589175

This is where I get the black LED acrylic:

https://www.tapplastics.com/product/plastics/cut_to_size_pla...