Here’s a very informative step by step tutorial clip to demonstrate the process of molding fiberglass composites. A similar method was used to produce all fiberglass parts of the costume, including the helmet. The same method will be used to for instance reinforce the inside of the ABS helmet.
The concept behind resin and fiberglass (composite materials) is that fibers (either glass fiber, nylon, kevlar etc.) are soaked with a form of resin over a mold. When the resin fully hardens (by use of a catalysator) we have a composite material! The advantage with composite materials is that the resin provides a very hard, stiff and scratch-resistance surface, while the fibers (which are sandwiched and soaked “between” resin) improve the flexability of the composite. Resin and aramid/kevlar fibers are used to produce bullet proof helmets. When the woven fibers are sewn together in layers, it provide protection for shrapnel, blunt weapons or projectiles, which is the basis behind commercial bullet proof/flak vests. So now you know that.
Hypothetically speaking, if aramid/kevlar fibers were used instead of the regular cheap fiberglass to produce the Threepio parts, it would be “bullet-proof”. Well, this of course depends on fiber orientation, thickness of the parts, geometry and other factors, but how cool wouldn’t that be?
How awesome wouldn’t it be to for instance stop an armed robbery as See-Threepio? Ironman, go to bed..