Most sound people don't get the assignment to create worlds of sound and get freedom to try a lot of things and then get the scrutiny and support of the team over a long period of time.
Ben BurttI've always found that when you're trying to create illusions with sound, especially in a science fiction or fantasy movie, that pulling sounds from the world around us is a great way to cement that illusion because you can go out and record an elevator in George Lucas's house or something, and it will have that motor sound.
Ben Burtt