I did this project as I needed a new clock and I had an only Raspberry Pi lying around unused and I also wanted to use my new 3D Printer.
The idea was simple, buy an LED matrix, connect it to the RPi, then using python write a very simple clock application that would auto-start on boot.
The LED Matrix uses a MAX7219 Chip driving 4 8x8 LED Matrix boards. This easily connects to the Raspberry Pi via the SPI interface.
Then a quick google search revealed the Python Luma LED Matrix Library. This library nicely wraps the SPI interface and abstracts the display to an easy to use "Canvas". It even allows you to set different fonts :)
After playing with the library for a bit I discovered the silly-clock.py example. I used this as a base, removed some of the "silly" bits, changed the font. This gave me the perfect clock for my project.
https://raspi.tv/2013/8-x-8-led-array-driven-by-max7219-on-the-raspberry-pi-via-python
Installing pip:
sudo apt update
sudo apt install python3-pip
pip3 install luma.led-matrix==1.6.1
sudo apt-get install libopenjp2-7
sudo apt install libtiff5
https://medium.com/codex/setup-a-python-script-as-a-service-through-systemctl-systemd-f0cc55a42267
Copy service/clock.service to /etc/systemd/system/clock.service
sudo systemctl daemon-reload
sudo systemctl enable clock.service
sudo systemctl start clock.service