Well, on one hand it really shouldn’t matter much, however, if you build a
traditional frame, you need the plywood to be as stiff as possible, so you want
a hardwood plywood.
If you build one of the alternate frame designs (or whatever is going to be the
new official design in the next month), then the plywood isn’t really a
structural piece, and the cheapest thing you can get will do.
With the ‘alternate 2’ frame that I’ve posted a few places, I will probably step
down to 1/2" plywood as it has 2x4 pieces supporting it’s width and that would
allow me to use 1/4" plywood wasteboard and still cut a 3/4" piece and have it
flush with the bottom beam (eliminating problems cutting down close to the beam)
k