This is a Halo Reach - Mark 5 B Style Helmet with Optional UA (Up Armor) Helmet add on.
This model was taken from the following 405th.com pepakura armory files:
Modeler: JTM1997 Unfolder: mkshane81
Up Armor add on:
Modeler: ReachWOutSmoother Unfolder: MissingSpartan7
These people are awesome when it comes to unfolding and modeling.
I just dressed it up and made the models printable for the 3D printer. You can print the helmet by itself or print the add on separate and add it later. It may require some fine tuning.
I have not printed it yet but it shows successful through simplify 3D so enjoy.
WARNING - You may want to resize this to fit you as it currently is set to fit my fat head.