Here are the files shared on Thingiverse.
Halo 4 Helmet Medium Size B by big_red_frog - Thingiverse
It has 15 pieces and they range from a couple hours to probuly 8 hours to print. So this took a very long time to print. We just keep it printing just about 24-7.
Here is a time lapse video of one part being printed.
Filament cost from $21-$40 a 2.2 lbs shipped. The helmet took about $19 worth of filament to print. I buy my filament in bulk now so it saves money.
3D printing takes some tinkering to get the first layer right. It is not as easy as a ink jet printer at this point. But most people on this group would not have an issue with it.
Yes it fits my boys head he loves it.
This is printed out of PLA but I can print ABS same stuff Legos are made out of so it is strong.