The first tests of the contsruction method included round holes.
These were intended for the WS2811 (through hole 8mmm diffused) leds but they didn't work well with the FastLED library and I used the leds cut from WS2812B neopixel strips from adafruit.
And off course some coding involved. The first real scripting I ever did in arduino's c/c++ based language. Took me a day but it didn't turn out too difficult. I made use of the FastLED library which makes it possible besides the classic RGB to also adress the led colours as HSV values.