I used to run a motorcycle towing service in Southern CommieFornia.
Anyway, some motorcycle manufacturers ship their motorcycles in steel frames that are wrapped in thin plywood sheets, about 1/4" thick, clean BRAND NEW plywood.
Believe it or not, they throw these large plywood sheets away! Other motorcycles are shipped in wooden crates, and likewise, they are sometimes wrapped in NEW THIN plywood sheets to prevent damage to the bike during shipping. Also, larger vehicles like quads and "mules" come in plywood crates.
Think outside of the box, and you will find sources for FREE MATERIALS to use for arts and crafts, etc.
Call you local BMW, BUELL or DUCATI, Honda, Aprillia, Kawasaki or VICTORY motorcycle dealership and ask about these plywood sheets. They are usually about six feet long and 40 inches or so tall, and about 1/4" thick or less. Don't tell them you plan to make money with it. They will want to charge you for it. Just "offer" to haul it away for them. Tell them you want to tinker in your home hobby shop, making bird houses to hang around the neighborhood!
Joe