How to mold a Vader dome

[DarkHelmet]

I'm really really enjoying sculpting. After finishing my Hollywoid gorilla, I am moving on to my next project/learning experience....my own Vader.

Molding the face is straight forward, but how do you cast and mold the dome with the big gaping space for the face?

 

[Scote]

Hi, just look at the making of of episode 3