Here is the first in a series of tutorials on making a foam helmet:
I'm following this as much as I can.
I started by making a foil and tape pattern blank by wrapping an old racing helmet.
Cutting off the foil/tape. I forgot to take a pic of the lines for the pattern pieces, but it's about the same as the tutorial.
You don't really get a sense of the size here, but it's gigantic. I mean Space Balls sized. I just scrapped it. I've gotten into 3d printing and will just attempt to print out a rebel pilot helmet instead.