Buzz ought to consist of a large number of discrete parts, all parented to the bones of a relatively simple armature. Define the whole thing as a “group.”
The various “making of” pieces that Pixar has released indicate that the real Buzz model contains over 100 different materials.
Wired Magazine just published a short piece (basically lifted directly from Pixar’s own web-site) which illustrates how a single shot from Toy Story 3 was assembled. And what really stands out to me is that the next-to-last photo looks “very ordinary.” But then, move ahead to the final render. Compare the detailing on Buzz and Woody to the lesser detailing applied to the characters in the back. Notice how the light has been manipulated.
There are many layers of effects here, even though Pixar has found a way to merge them all together in just one run-through.