Abstract: A low cost process of particular utility in manufacturing optical grade objects such as mirrors from a plastic sheet, comprising the steps of selecting a predefined three dimensional shape to be formed and machining a block of a microporous material, to provide the selected three dimensional shape on one surface thereof. A sheet of plastic is placed over the machined three dimensional shape and distanced therefrom. The sheet of plastic is heated a vacuum is applied through the microporous material to draw the heated plastic sheet to conform to the shape in the block. A surface of the conformed shape plastic is metallized to a form an optical mirror surface.