The printable files here are the casing for the Christmas tree lights, print them and snap them together encasing the WS2812b leds, for protection and diffusing.

Vitamins needed:

144 led per meter WS2812 led band, it should look like this:
x meters of 3 wire flat cable (I've found 6 wire one and split it in 3 wire strands) - green if you can find it!:
an ESP32 based board (most of them should do as long as you can upload the firmware on it)
a straight cutting tool to separate the leds from the band
a good wire insulation stripping tool to be able to strip the insulation
a good soldering station with a fine tip
a great amount of patience
some beers :)
PLA your choice of transparent/natural

Preparing the ESP32:

This project would have been a lot harder to make without the awesome WLED project https://kno.wled.ge/ !

Please follow the instructions over there to install it on you ESP32 board before starting the leds, it will help having it ready so you can debug your soldering.

Step by step instructions:

Figure out the total length you want for your lights - I've gone for 5 meters, 50 leds spaced at 10 cm, you can go crazy with this just mind the power requirements
Source the vitamins
Cut the leds out of the led band - this is where the straight cutting tool is of importance I used the scissors from a swiss army knife so I could cut the pads between the leds trough the middle, like this:
prepare your wires - cut them to required length, strip and solder clad them:
Solder wires to leds (mind the direction arrow, base should point to last led in chain):
Test often to make sure all solder points are good! Plugin the ESP32 and make sure all leds light … unless you are over 30 which is the default setting in WLED.
Once you reach your required length you can print the covers and install them (standard prusa 0.20 mm speed, prusament PLA, 20% infill) :