Usually for those, most I've heard used were corset's with steel boning. It'll allow you to retain shape while giving you maximum stability.
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RWBY: Blake Belladonna - Gambol Shroud FUNCTIONAL
RWBY: Pyrrha Nikos - Milo FUNCTIONAL
Planned Cosplay 2014
- Winged Armor Year: Tentative
Pegasus God Cloth - Silver [Saint Seiya]