Very nice. I like the design concept but like others, think the Baltic Birch would be the way to go.
I am doing something very similar for one of our products (not speakers) out of 1/2" Baltic Birch ply. If the sides are aligned properly and/or sanded smooth, you also have the option of veneering if you don't like the Baltic look. Sealing Baltic Birch ply is not that bad as long as it is cut with quality, sharp tools. A CNC should do the job nicely as long as the bits are new.
I think you should send me a pair

. I have some amazing veneers that would look sharp on these speakers
