One of the noises of Wall.E's treads comes from a hand-cranked generator that Burtt saw in an old John Wayne movie and tracked down on eBay.
"I saw the film and thought, that sounds like Wall.E! Then, when he moves faster I used a more high-pitched sound from a machine called an inertia starter that was used to manually crank up 1930s airplanes."
For the more hi-tech Eve, Burtt created the sound of her laser blaster by hanging an enormous slinky from the ceiling and "twanging" it with scraps of metal.
There's a lot more, so check it out.