Abstract: A bottom tool/bending die for use in sheet metal forming. The bottom tool includes a pair of movable dies that provide substantially continuous support of a work piece as it is being deformed. Each die includes an upper surface configured to contact the work piece and having an inner and an outer edge. As the die moves in the tool, the inner edge of the upper surface is closer to a center of rotation of the die than the outer edge. In some embodiments, the upper surfaces of the dies are shaped so that a fixed separation is maintained between the inner edges of the dies as they rotate. In at least one embodiment, sector gears are used to control the motion of the dies.