The first thing I had to do for this sign was cut all of the wood to the size I would be using. I used the miter saw to cut everything to length. It is helpful when you can set up a stop block for repeatable cuts that way you know they will all be exactly the same dimension. My shelves were 24 inches wide. Here is my cut list for the three shelves I made.
(1x4) 6- 22-1/2”
(Dowel) 3- 24”