Abstract: A first mold is provided having a first molding surface including a flat primary surface area, a plurality of spaced leg areas within the primary surface area, and a plurality of pin holes in the primary surface area positioned between the leg areas; and a second mold is provided having a second molding surface including a flat primary surface area, a plurality of leg areas in the primary surface area corresponding to the leg areas in the primary surface area of the first molding surface, and a plurality of spaced knitting surfaces relieved from the general plain of the primary surface area, positioned between the leg areas, and corresponding to respective pin holes in the primary surface area of the first molding surface. A first plastic sheet is thermoformed to the first molding surface to conform the first plastic sheet to the primary surface area and the leg areas of the first molding surface and position the sheet in overlying relation to the pin holes.