an upper thermoforming mold is positioned above a lower thermoforming mold on a platen . the platen is provided with an array of position - controlled hydraulic cylinders . a controller drives the array of cylinders to uniformly advance the two molds together once heated sheets of thermoplastic material have been formed thereon . by controlling the position of each actuator , forces may be applied at different levels to the platen to bring about uniform molded parts and reduced deflection of the molds .