An apparatus for forming a shadow mask from a mask blank includes a punch having a convex surface, a pad having a complementary concave surface, and upper and lower dies having openings therein for receiving the punch and the pad, respectively. Each die also has a complementary nonplanar surface adjacent the opening for clamping the mask blank. Each die surface has a surface contour that substantially matches the extended surface contour of the mask blank when the mask blank lies against the inner edge of the lower die surface, so that wrinkling does not occur when the mask blank is clamped between the upper and lower dies.