Nick and his team transformed humans into bizarre alien species using rubber masks, makeup and body suits. They also built radio-controlled puppets and animatronics that achieved an amazing range of movement and facial expression. For Episode I, they built a new younger Yoda puppet. Strikes Back , they found there was little to improve upon. They streamlined a few things and built it with silicone instead of foam latex.
Silicone is a translucent material that allows for greater detail and flexibility of movement.
They made additional improvements after talking with Frank Oz , the voice and puppeteer of Yoda. I Yoda has a radio-controlled smile mechanism and eyebrow movement. Deciding which method to use to create a creature effect depends on the answers to some very practical questions, says Nick, including cost, time, and prominence of a character in the film. If a character appears only in shadow in a few scenes, CG is probably too expensive an option and they might decide to use makeup which can take four to five hours a day, or build a rubber mask and body suit. For some characters that are entirely CG, Nick's team built stand-in puppets or properly proportioned costumes so the actors would have something real to react to during shooting.