Hi there!
The information you need is in the Costume Reference Library on 501st.com
http://www.501st.com/databank/Costuming:TK_anh_stunt
"The armor parts shall be made from one of these types of materials or like materials: White fiberglass, ABS (Acrylonitrile Butadiene Styrene), HIPS (High Impact Polystyrene), or Polyvinyl chloride (PVC)."
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