the types disclosed in the aforementioned u s pat no 3 553 787 and u s pat no 4 018 551 and the details of the operation of such plastic forming apparatus may be found in such patents briefly summarized the apparatus 10 includes a forming table 12 arranged on wheels 14 for movement between an extended position as shown in fig1 and a retracted position at which it is located directly beneath an elevated heating oven 16 the forming table 12 includes a bed 18 provided with a plurality of support members 20 on which forming molds not shown having a variety of sizes and shapes can be supported a frame 22 is associated with the forming table 12 and is mounted on movable supports 24 for raising and lowering the frame 22 with respect to the bed 18 and the mold supported thereat in operation the forming table 12 is moved to its extended position and a desired mold is placed on the bed 18 while a sheet of generally flaccid plastic material not shown is mounted on the frame 22 with a plurality of clamps 26 being provided on the frame 22 to clamp the side edges of the plastic sheet against the supporting surface of the frame 22 to hold the plastic sheet in place on the frame 22 the forming table 12 is then.