If you plan to use wonderflex to make his armor, what I suggest you do is make a cardboard version of it first. Then, once your done with that, heat the pieces over it and you should get it the shape you want. Remember, this armor will probably need to be made into several pieces. And if you want to make it look really smooth, look more into resin and fiberglassing.
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If you need help on props, PM me and I'll try to help you.