Reply by casual1carpenter

Rayban, is there a plywood wholesaler near you? The kind that sells to the trade? The place I go to stocks 4’ by 10’ plywood with birch, maple, white oak, cherry etc, but it can be a bit pricey for a painted unit. They do counter sales on a cash customer pickup basis.
As to the glue up, it would be no different than a tabletop. If you follow all the rules (the ones that I don’t know, lol) it should allow for expansion – contraction movement but did you consider cupping or a even slight radical twist? Today I trued – s4s – a premium SPF 2×4 that I have had for quite awhile stored in a rather warm shed. I could sort of feel the sap wetness of the wood. They will serve their intended purpose of clamping cauls to position, align and clamp an accurate 45 degree – 22.5 lock miter joint, but I have my doubts as to how long they will remain accurate.
Just a few of my thoughts for you to consider, but I’m casual – pre-rookie stage and I often do things more than once because well I’m often not happy with the final result. I try. I goof up stuff too.