 An addition to the effects department was Mike <unk> , who served as Meddings ' assistant in designing vehicles and buildings . Meddings and <unk> jointly pioneered an " organic " design technique in which the exteriors of models and sets were <unk> with parts from model kits and children 's toys . Models and sets were also " <unk> down " with powder paint or pencil lead to create a used look . Toy cars and <unk> were used in long shot , while scale vehicles were equipped with basic steering and suspension for added realism . <unk> fans and <unk> <unk> , which are capable of issuing air jets or chemical exhaust , were attached to the <unk> to simulate dust trails . Another of Meddings ' inventions was a closed , cyclical effects stage nicknamed the " rolling road " : consisting of two or more loops of canvas running at different speeds , this device allowed shots of moving vehicles to be filmed on a static set to make more efficient use of the limited studio space . Airborne aircraft sequences were mounted against a " rolling sky " , with smoke fanned across to simulate passing clouds . 
