The helmet offers a fully textured cap that is printable and fits directly on top of the face mask portion and is scaled for a 23" circumference head. I managed to fit it on my larger noggin but for comfort, I'd give it a few points of scaling. With the mask being separated, the flat top provides a fantastic print surface.

The rest of the hard parts can be affixed to your costume as you see fit, but have a natural curve to make it easier to attach.