The first thing one would need to know is what the finished piece, or head, is going to be made of, then one can make a decision on what to make the mold out of, and how to make the mold.

I'm gonna make it out of foam latex for the first time, and I wanna get all the details around the eyes, etc.

Thanks

Well, I think you sculpt the original clay model out of drying clay, or something like that. I recommend looking into getting stop motion books such as Stop Motion: Craft Skills for Model Animation. The book covers most every aspect of making an animation, somewhat loosely, and has a decent section on building/ setting up molds and then making the latex puppet.

Hey Marthia,
There is no way to make an Ulracal mold, and not destroy or at least damage the original sculpt, sorry.
Just wondering why you need the head made out of foam latex? is there going to be some sort of movement in the face?
As one who has been there, if you don't know how to make a mold, than foam latex might be a bit out of you league, you might want to start a puppet with some easier materials, unless the goal is to make a puppet out of foam latex.
Depending on what the puppet must accomplish is usually how we decide what materials the puppet is to be made of, if that makes any sense.