I have also been working on a way to improve the looks of my LED display - nothing so impressive as ThrowingChicken’s masterpiece, but a different approach you may find interesting:
I had some decals made up with black surround and silver metallic features, placed the decal on the back side of a laser cut 1/16 clear acrylic piece, and then set it on top of some laser cut lenticular material (gives it the vertical patterning). This was not dark enough so I placed some car window tint material on the backside (smooth side) of the lenticular material and it looks much better.
Here is the latest version that has a 3-D Bezel printed by AJ, laser cut plexiglass with decal of metalic contacts and black surround and the Lenticular material with window tint (so you can’t see the individual LEDs when they are off):
