I have only one question for you, helmet lord: Did you use any type of base for this helmet? If not, then how did you build this master piece? Or can you please send me a link to a tutorial on how to make this beautiful helmet, please. I'm gonna use at a comi-con sometime!
The base for the helmet is actually cardstock paper, you download the pdo file basically its the blueprint of the helmet, cut out all the parts glue and fold it all together, its called papercraft or pepakura, then you harden the helmet with fiberglass or casting resin, bondo the outside to smooth it out then paint it.
If you want to make your own, the best place to learn the process would be the 405th forums there is tons of stickies with tutorials on how to build not only the helmet but the whole suit and weapons, also they have most of the files for any halo based helmet and other games
go to this link---> 405th.com
hope you get to build your own Good luck, and thanks for the comment