An idea.
For rigid and flexible they could look at how the scales along a snake's belly move. Now those have to be rigid, flexible and light. They don't operate against a 14.7 pound pressure differential, though.
I'm sure some Kevlar or similar material could be manufactured to be thin and flexible.
NASA's insistence in not having an air bladder isn't understandable from what I know now. There has to be an air bladder inside the suit. The suit is an air bladder.
Wonder what the pressure is inside a space suit?
Arf