Regimas, if your using plastic then all you need to do is find a centerline at the chest plates where it meats her bust curve and bend it outward. This will give you a slight V in the armor which will fit a bust fairly well. Thats how most plastic female sets are done up.
Fiberglass is much more difficult. You have 2 ways you can do it, one is you can use the plastic piece as a base, sand it, then put bondo over it and sculpt a nice curve over the front. Thats about the easiest way to do it with fiber without sculpting your own mold and casting it.
Metal...well thats pretty darn advanced. Cold dishing you need to work the metal around the sides with your hammer moving inward. Gradually you pick up the hammering in the middle till you get a nice slope down then across. Hard to explain but takes months to become adept at.
I'd go with plastic.
MandÃƒÂ¡lii kote. Eran, vode, c'rtÃƒÂ¤! - Mandalorian Glory. We, brothers, stand as one!
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