This is actually a good possible answer to the undersuit.
If you look at the page on the link below, this guy has sculpted a muscle suit and casts it in sections. The sections are glued to a bodysuit in position to fit the person who is going to wear it. The armor parts are cast from latex and have some flex to them. I'm changing my idea on how to do the bodysuit after seeing this. I think this is the way to go...
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