When I replaced the original interior doors in my house, I repurposed the flat hollow-core luan wooden doors for use as building tables/boards. They are normally about 78" long and can accommodate building most larger size planes. Widths may vary from 2 feet to 3 feet. Push pins can penetrate the wood door skin to hold parts in place. I kept a couple of doors for myself and gave the other 15 doors to my fellow club members, who gladly scarfed them up and put them to good use. The doors can be set on saw horses or can be laid on a work bench as a flat building surface. Just be sure to shim them if needed to make sure they are level and flat. Luan wood doors can often be found cheap at building salvage companies.