I have seen the way I can make the mold for my current project, Twisty III. I guess that’s what time off, taking trips and seeing new stuff does for for you. This is a sketch for the mold which will do the hollow head part:

This is a top view through the head. It will be a 4 part mold with a core piece that is meant to be cut away after the wax is poured into the mold and removed. The mold is made with effectively a solid head, but designed in a way to be easily removed from the cast part, making a hollow head. Easy that is, if it is wax, which is soft enough to be cut out with small tools. Much more difficult to do in a hard material like plaster or plastic. Seems this is going to be a bronze project after all.

This is a side view of the core piece to be modeled into the head cavity from the angle of one quadrant:

It will still take two more parts at least to do the body, so a six piece mold is going to take some time to do, and will be the most complicated ever, for me. It is going to take time. Gian Lorenzo Bernini, the greatest sculptor that ever lived, could do this; I should at least try.