Step 2: Head Patterns, Mold, Gourd
The original clay sculpture is on the left. Then Zhang made a latex rubber mold over the original, pulled it off, and cast hard rubbery plastic resin in that. That's the white version standing to the right of the original.
That white pattern was used to cast the mold you see here.
This particular mold has a rubber interior and plaster around that to support it.
From left to right are the original carved pattern, plastic resin duplicate, and an actual gourd grown in the mold.