This is basically a LED matrix, with a cardboard mask in front. I decided to go for a 12x12 LEDs, one every 2 cm, so in total 24x24 cm.
- Draw a 12x12 grid in the center of the base board
- Attach the LEDs at the midpoints in the grid, wire it up following the exposed pads in the LED strip
- Insert the Raspberry pi and wire it up too
- Add a power connector on the back, and wire the +5V to the raspberry pi and the LEDs
- Build the plastic/foam separator to isolate each LED from the base to the front
- Carve the cardboard in front with the letters

Follow the Software instructions post with the steps