I've been talking with my dad, he was saying that paper mache is a hell of a lot easier to work with since you can shape it to the form you want easily, as with fiberglass you have to work really hard to bend it around a corner.
OH! something completely cooler i just thought of that I've never seen mentioned before on these forums. I was thinking of art class and remembered this paper mache like stuff only it was thin cloth-like sheets of plaster that you soak in water to activate. It's called plaster gauze or plaster cloth, google either one, it's the same thing. But I definitely think you should use this.