[Qbot2640]

Be careful interchanging the terms "Birch" and "Baltic Birch". The former is just an appearance grade plywood with a birch veneer for cabinet making. What you really want for a strong bellypan is the latter - Baltic Birch. The core layers are solid birch as well as the outer veneer, and with no voids. This material is excellent for many robotics applications. It is light, strong, and holds screws extremely well. "Just plain birch" plywood is attractive, but the inner cores are made of a cheaper grade of wood and can contain voids and imperfections.

Also worth noting, American plywood is getting thinner - often you will see 23/32 rather than 3/4. The Baltic Birch is a European product, thus it is usually available in mm sizes...the 9mm is a great thickness for bellypan - a hair thicker than 3/8.