Gary,
I consider my plywood find a major triumph, both for quality and cost.
I was having trouble laser cutting the thicker (1/8") plywood and after a lot of research I found that the glue normally used to make plywood is not compatible with laser cutters. It just chars and absorbs the energy so you don't get a clean cut.
I eventually found a manufacturer of custom plywood that makes plywood using melamine glue which is laser compatible.
AIRCRAFT PLYWOOD MFG.
They can make the plywood from 1/16" up and in a wide range of wood types. They are MIL Spec rated and used on full size aircraft too, so great quality.
Initially I ordered a sheet of 1/8" all birch 5-ply and it was great. Cuts well on my laser cutter. Minimum order is a 4ft x 8ft sheet, but he will cut it down to 2ft x 4ft for shipping. I then take the 2ft x 4ft sheets to Lowes/ Home Depot and get them cut into 24" x 16" sheets to fit my laser cutter bed.
For the plug I ordered 1/16" 3-ply birch laser friendly (melamine) plywood. I think I used just over 4 4'x8' sheets for all the bulkheads.
The best thing about this supplier is that even though they are a custom ply manufacturer, the prices work out to be less than half what we normally pay, per square foot, from our usual 'hobby' suppliers.
I am phasing out all of my other plywood and migrating to these folks when I need more.
No hesitation for recommending this place for anyone that needs quality plywood.
Paul