A method of stretch forming a double curvature panel having corrugations or other surface features formed therein includes providing a reconfigurable forming surface defined by a flexible interpolator sheet mounted on an array of height adjustable pins, the interpolator sheet having a profiled upper surface adapted to form corrugations or other surface features in a workpiece as it is stretched over the forming surface, adjusting the height of each pin to suit the shape of the panel to be produced, placing a workpiece onto the forming surface, and stretching the workpiece over the forming surface such that the profiled upper surface of the interpolator sheet forms the desired corrugations or other surface features in the workpiece.