This a light diffuser for an 8x8 neopixel led array. This is an array from AliExpress labeled CJMCU-8*8. This will not fit neopixels from Adafruit. They are a different size.

The included lens can be printed with clear pla, or you can use a piece of white paper or anything translucent you want.

The components aren't exactly square, so if it doesn't seem to fit, try rotating parts.