Does anyone know how to mold a hollow head?

[Faydreams]

Any extra holes would be to allow expansion gasses to escape. It could just be heat bonded together, melt just enough and they'll bond as they cool.

I'd say you are right about the heat bonding thing. I have a few heads (barbies) that look melted in that area around the seam.

[MeltedCaramel]

I found this:
http://blog.tspadventures.com/2006/03/b ... china.html
And this:
https://www.youtube.com/watch?v=5SbSeNPwpAI

Both go a little way to explaining how they do it, but I'm thinking the rotary mold is involved big time here. I might try and figure out how to make ceramic cold casts to pour silicone in and just make heads the hard way, one layer of sillicone/pvc/whatever I end up using at a time. Either that or I may try the core mold method and try and pop the core molds ouf of the top and get a heavy grade heating wire/gun to manually attach the headcaps. *Sighs* What a pain in the behind!

[DollyKim]

The Alumalite company makes home casting products. Their smaller kits are good for experimenting.

There is InstaMorph low melt plastic that might give you what you want. Friendly Plastic can be manipulated with the average hot knife tool or 300 degree and under craft oven.