Due to their low weight and the fact that they had only one control wire per leg , the puppets was unable to walk convincingly . Therefore , scenes involving movement was filmed from the waist up , with a puppeteer holding the legs below the level of the camera and using a " bobbing " action to simulate motion . Alternatively , dynamic shots was eliminated altogether : in an interview with New Scientist , director of photography John Read spoke of the advantages of circumventing the lack of agility so that the puppets " appear , for example , to walk through doors ( although the control wires make this impossible ) or pick up a coffee cup ( although their fingers are not in fact jointed ) . " Live @-@ action shots of human hands was inserted whenever scripts called for more dexterous actions to be performed .