"We had an electronic head and arm for Threepio, and I manipulated the mechanism with a joystick. But it wasn't working. The propman said, 'Give me fifteen minutes.' We all went to get coffee, and when we came back, Threepio's head turned perfectly and his arm moved naturally. I looked up and realized that the prop man had a fishing pole with a fine nylon string attached to Threepio's arm. He had rigged another string around the head, which Chewbacca was holding. As Chewie moved his hands, Threepio's head turned!"
So said, Irvin Kershner, the director of a truly great film, The Empire Strikes Back.