We used sheets of white melamine covered particle board we bought at Lowe's. It's very sturdy and the smooth surface is kind to fabrics. You can get iron-on melamine tape to trim the edges. It isn't a lot more expensive than plywood and looks great. We used it to make a wide countertop between two storage cabinets, and to top a work table my husband made from 2x4s. It does not bow in the middle at all because it's so heavy.