There were many LED painter PCB companies in China

The LED Painter PCB is very simple

Most components may be in your junk box already.
The PCB is a two layer PCB with a blue solder mask and white silkscreen.

The LED Painter PCB grouped by color

The LED channels on the PCB are grouped for easy connection of red, green and blue LEDs.
In addition, each group also has power connections to make it easy to connect 48 individual LEDs.
Of course, the detail number of LEDs depend on your PCB project.

There were many LED painter PCB companies in China.

The LED Painter PCB is easily populated with the components listed in the bill of materials (BOM).
Some PCB companies will need you order PCB components by your self.
This mean you can finish your PCB project by you self.
You can create large arrays of LEDs using multiple LED Painter PCBs.