 In the show, Henson began experimenting with techniques that changed the way in which puppetry was used on television, including using the frame defined by the camera shot to allow the puppet performer to work from off-camera.He believed that television puppets needed to have "life and sensitivity" and began making characters from flexible, fabric-covered foam rubber, allowing them to express a wider array of emotions at a time when many puppets were made of carved wood.A marionette's arms are manipulated by strings, but Henson used rods to move his Muppets' arms, allowing greater control of expression.