I wanted to make diffusers for a kit that came with user-facing LEDs, since looking at bare LEDs sucks. I wound up with a shape that is sort of like a hexagonal gem shaped cap that fits around the 8-LED Neopixel rings (the knockoffs, not sure if the official Adafruit versions are the same size). You can turn it so it either makes the lights look like wedges, or if you turn the ring slightly, they look like lines. I printed these in clear PLA, but another material might work better. Otherwise the LEDs are still too bright to look right at, unless you turn them way down in code (I used 10 out of 255 brightness).