I noticed that the shelf was missing when I picked up the arcade. This is one of the main reasons why I wanted this cabinet. I wanted to be able to pull-out the drawer and switch games without having to move the game. This will be extra helpful in my shop!
I was able to get the dimensions from KLOV member, vegas12. A big thank you to him!
Once I had the dimensions, I actually had a spare piece of wood that I cut to dimensions. I tweaked it a little bit, but am happy with the result.
Now that the shelf is complete, I will be able to attach the control panel to the shelf.