Making a ceramic porcelain ball-jointed doll involves a lot of stages, and I soon discovered that each stage had its own set of "trade secrets."
So, I sculpted from polymer clay, and assumed that the shapes could be made into plaster molds, and then into porcelain.
While I was learning to sculpt, I also proceeded to make plaster molds for some parts which I thought was acceptable for the next stage. The reason for this is that I also needed to learn how to make plaster molds, even while I was just learning to use polymer clay.
So while I was also learning how to make plaster molds, I proceeded to make the ceramic slip and pour them into the molds that I had made.
Experience, and going through all the processes / stages are the only way to learn, and I went through a lot of trial and error. Even now, I would not consider myself halfway to becoming an expert.
The head pictured above was my first ever doll's head that I was able to make. Eventually, I was able to match the head with an acceptable set of parts, but I decided that I was torturing myself, in a way, because I had too many parts to manage. I made a torso with detachable / movable breasts, and shoulders that could shrug, and toes that can tiptoe. I also separated the neck from the torso and the head. Then almost overnight, I woke up and thought that I was creating something that was too tall, and I suddenly wanted a smaller doll! So I stopped working on this one, and started work on a smaller doll.
I would probably go back to making this first design later, but not yet.