[Sayantan Pal] did this for the humble RGB LED matrix, creating an extra-thin version by recessing WS2812b NeoPixel LEDs ... used PCB thickness. Using EasyEDA, [Sayantan] designed a 8×8 matrix ...

the beauty in its design lies in the detail he places on the PCB layout. In this case, the layout is a bit easier than some of his other work needing only to arrange the blinking LEDs in a “Y ...