A more polished and properly hulled version of the helmet I worked on as part of MET hackathon. I've included two versions: a full helmet, and a halved helmet with a chopped bottom.
Geometry problems should be mostly solved in these versions. The full helmet requires full support, and a lot of it. The halved version is a leaner print, which doesn't require support material. I've taken a little license with the ear holes to get rid of odd looking areas where the design was sliced, and to put space for where your ears might end up if someone actually built a human-sized version.
The awesome thing about this print, is that the helmet its based on isn't on display at the MET, it's in storage - I worked off a 123D Catch created by MET staff. You can't see this at the MET, but you can see it in your own home thanks to 3D printing!