I was corresponding with Tom from Evil Toad Studios after he sent me an email and an elegant new direction for ball jointing. He sent along some photos which I will repost with his permission.
When asked whether these were cooked together, and If so, how would you keep them from sticking, his answer was very clever and easy. He used a heat gun to partially cook the first piece of clay. -How intuitive is that?- He said that when you partially cook it, it should be leather hard (A ceramics term for greenware or uncured clay) before you can put the second joint on this.
I think this is a really clever Idea. The only problem I can see is once more.. Strength when you start working with smaller joints.
In my mind, there are two solutions for this. 1. Do it in ceramics. 2. Do it in polymer clay and finish with fiberglass resin for strength on the outer joint.
After making my first I realized that I had missed an important idea in what Tom had sent. The joint needs to be able to make a straight, and a ninety degree angle. This will be important in doll making for sure. (ie knees etc)