Most armor costumes you see (ex: Iron Man, Mass Effect, etc) are made of EVA Foam, cut and glued together, dremmeled for weathering, and painted. It's flexible, strong, formable, and cheap. EVA is commonly used in interlocking foam floor tiles from hardware stores, automotive centers, and even discount stores like Big Lots or used in yoga mats. It doesn't matter what color, you're going to paint it anyway! Mad props to BioWeapons for creating the happiest set of armored boobs I've ever seen!
Idea for vow renewal: Burn a note that says "here's to the past", and release a note that says "here's to the future" tied to a balloon. Secure it in a ziplock bag and ask who ever found it to mail it back to us so we know how far it went :)