A method for making a forming structure for use in an apparatus for making formed polymeric film. The method comprises a multiple step process of applying a photoresist polymer to a metal base sheet, curing the polymer, acid etching the portions of the metal base sheet not covered by cured polymer to form a protrusion having an upper surface and a side wall (or walls), washing the base sheet with caustic and repeating the process as necessary, each time covering the upper surface and side wall of the protrusion with cured polymer.