Just a quick solution to provide some diffusion, stand the matrix up and hold the MCU.
Printed in white PLA, I used 0.28mm layer height and plenty of light gets through the single layer front.
2 x 3mm (x 7mm? long) bolts hold the NodeMCU (note: V3 used) to the stand as I wanted a stand alone option for other jobs, the stand holes are 2,5mm and designed to be tapped, the nodemcu part has 3mm holes.
The LED matrix was designed to have a rear but the matrix is a tight fit and is not falling out, need to tug by the wires to remove. Not going to bother for the moment.
This is made for a chinese LED matrix, it uses WS2812B leds on a 10mm pitch exactly, overall matrix size is 80.0 x 80.0mm.

Note I removed the excess wires and resoldered the input wires .. this matrix has a great deal of heat transfer ability (aluminium substrate maybe) and this killed the LED directly under the wires, I had to swap it with the last LED on the matrix, hence the one black corner .. so be warned if you want to resolder these.

Leds as photographed are at around 10% brightness as I am only using a 600mA 5V supply and the matrix full power is 3.5A.

Added the arduion sketch too, its messy as it was a quick hack though others may find it useful, it was originally based on Neofire found on github so that is still in there, but then for the tree I added the neopixel library also and so a constructor exists for both a neomatrix and a neostrand in the same code.
I used OTA so I can upload mods without plugging it into the PC.
Still a work in progress, making the top lights more suitable, fixing stars etc..

Design files are for Designspark Mechanical