Why bother with the BB ply? I would use MDF and glue on a strip of hard wood for the contact edge. Joint the edge and you should be good to go.I’m making a shooting board using Rob Cosmans technique / video. It calls for 1” (or 3/4”) MDF base and Baltic Birch plywood surface. MDF is easy enough to find, but I can’t seem to find baltic birch in my area (upper midwest). Will other plywoods do? I would think it primarily needs to be very flat and square for this project but was curious if anyone had input on alternatives.