I tried to e-mail you some diagrams on how to cut this last week. The
mail comes back returned. If you want them then drop me an e-mail
with your correct address.

btw, I've used birch plywood from HD for control panels before. I
haven't had a problem with large voids in it. I wouldn't build
furniture with it but for control panels it's fine. I'm sure you've
noticed voids in arcade cabinets you've worked on.