Here is a quick start guide to help you put PLIB: Programmable LEDs In a Box together, familiarize yourself with the interface, and learn how to program PLIB.
PLIB: Programmable LEDs In a Box - Installing
PLIB's outer case has 10 layers of 3mm laser-cut MDF board, one 3mm acrylic sheet as the back cover, and one 2mm translucent acrylic sheet as the front cover. Each one of the PLIB's MDF outer layers is engraved with a number from 1 to 10, and they should stack together in this order.

You can also download this AutoCAD file if you want to modify PLIB's case and laser-cut it yourself.
Upon unboxing, you'll find PLIB's PCB boards neatly enclosed within the case, snugly wrapped in heat-shrink material. The case is correctly layered, but without the screws to hold them together, you'll need to attach the screws and nuts.
PLIB: Programmable LEDs In a Box - Interface
For PLIB orders without the OLED screen, you can still effortlessly navigate its interface using the WS2812 LEDs. There are five main levels: Charging, Color Temperature, HSI, Sound Visualizer, and Light Effects.
Simply give the knob a single click to power on PLIB, and you'll start at the default Charging level. To switch between levels, press the knob and turn it clockwise to cycle through Color Temperature, HSI, Sound Visualizer, and Light Effect levels. Alternatively, you can press the knob and turn it counter-clockwise to go back one level.
As you move through these five levels, the 16 WS2812 LEDs will illuminate in groups of four, indicating your current level. Notably, the Charging level is indicated by all LEDs being turned off.
Remember, double-click on the knob to turn PLIB off.
PLIB: Programmable LEDs In a Box - Control WS2812B LEDs

Right between the Type-C port and Type-A port, you can find pins for connecting and programming the WS2812b 5050 LEDs. The GND pin is in the middle and the Signal pin is closer to the Type-A port. Make sure when you want to run your own program for the WS2812 LEDs the PLIB is powered off. Here is a link to the FastLED library that you can use to get started with cool LED effects. https://github.com/FastLED/FastLED
PLIB: Programmable LEDs In a Box - Programming
If you decide to flash your programs to PLIB you would need a USBtiny AVR ISP Programmer/Bootloader.
Connect the Bootloader to ICSP1 on PLIB PCB.

Here is the schematic design and PCB screenshot to help you connect the bootloader properly.


Here is our source code, please consider reading and understanding the entire source code for PLIB first before flashing your own.
OK, my bad. I was expecting C code, not an Arduino sketch. There is source...
The zip above does not actually contain any source!