Step 4: Prepare the Middle Boards
If you messed up in the last step, the wood isn't lost, use it here!
For this step, all you need to do is cut a hole in each of the middle boards slightly larger than the size of the LED matrix, so all of the wires and electronics fit inside.
I did this by drilling out the remaining supports of a failed front board and using a chisel to clean it up. Repeat this for as many boards as you wish, I used 2.