Flexible plywood is designed for making curved parts, a practice which dates back to the 1850s in furniture making.
Aircraft grade plywood, often Baltic birch, is made from three or more plies of birch, as thin as 1⁄64 inch (0.40 mm) thick in total, and is extremely strong and light. At 3⁄8 inch (9.5 mm) thick, mahogany three-ply “wiggle board” or “bendy board” come in 4 by 8 feet (1.2 m × 2.4 m) sheets with a very thin cross-grain central ply and two thicker exterior plies, either long grain on the sheet, or cross grain. Wiggle board is often glued together in two layers once it is formed into the desired curve, so that the final shape will be stiff and resist movement. Often, decorative wood veneers are added as a surface layer.
In the United Kingdom single-ply sheets of veneer were used to make stove pipe hats in Victorian times, so flexible modern plywood is sometimes known there as “hatters ply”, although the original material was not strictly plywood, but a single sheet of veneer.