Here is my little guy, all geared up and ready to go!
This is a completely homemade costume. Just a cardboard box and lots of styrofoam. I used craft glue and some masking tape, too.
Just a note, if you attempt to make any costume using styrofoam, be sure to only use latex (water-based) paints or, if you plan on spray painting, be sure to "seal" the styrofoam with some masking tape. I believe that all spray paints will "melt" the styrofoam on contact.