Here is my process for making the mold for my puppet.
First I take the sculpt and bury it halfway in water based clay. It is sprayed with a coat of crystal clear.
Next I begin building up layers of ultracal on top of the sculpt and clay.
Wait five minutes and add another layer.
Burlap soaked in ultracal is added in the next layer to protect the mold from breaking.
Finally a super layer of ultracal is added and a few hours are given to let it set up.
Then work on the second half of the mold starts. The water base clay is removed and then cleaned off. The edges of the first half of the mold are filed to remove the sharpness.
Channels for a tight seam and being able to pry the mold apart are made out of water base clay.
A coat of vasoline is put on any part of the first half of the mold exposed and crystal clear is put on top.
Then the whole building up process of ultracal happens again.
Until finally the mold is set up and pulled apart.
The original pattern usually does not survive this process.
The last step is to clean up the mold, rinsing out the water based clay, pattern, and vasoline.