He's doing Pepakura, which requires paper/cardstock (as mentioned, use cardstock). You finish the product then paint fiber glass over it. You can also use bondo for extra stength. Then you actually paint it. People have made suits from all kinds of games. Halo, GoW, you name it.
I'm not saying you're wrong, I'm simply implying that, on occassion, depending on what the artist is able to accomplish, using more efficient mediums is how a more professional look is produced.
In his situation, though, your suggestion seems more fitting.