spray chrome paint. Several layers of paint on top of craft foam. Same withthe helmet, after it has dried you can give it a brushed aluminum look by lightly using a green scrubby.
Thought I would share with you all my first pep build. This past Halloween I won 2 costume contests with my War Machine Costume. I learned so much on this first build, I am looking forward to my next one it should be better than this was. I will mod this one so I can wear it to the WonderCon...