Keeping with the sculpture, I decided to make this little mockup to decide exactly how I want to build my robot. I was having a little trouble deciding exactly how do do the upper torso, but I think I've got it worked out now. I only did half since I only needed to figure it out once.
If it looks like a skeleton, it's because I used that as inspiration for my design. The narrow middle section will be hollow and function just like the larger abdomen section on dolls that have them, except it's aligned specifically with the spine to allow for more natural movement. I actually intend to cover the empty space in front of it with some corrugated tubing, which I hope will be able to bend with it. A similar narrow space will run up the back of the torso, and the neck is designed the same way. A disc stands in for the head because I hadn't taken out enough Sculpey to make one and didn't feel like warming it up (it's all crumbly when it's cold).
The other notable feature is the double-jointed shoulders. I realized that an arm that fits directly into a rigid torso is not able to make the full range of motion that a real person's arm can. Try lifting your arm straight up without moving your shoulder. You can't! So rather than mimicking the full skeletal structure of collar bones and shoulder blades (that would be too complicated), I just stuck in an extra joint, which should have roughly the same effect. It doesn't look very good here, but it should actually be a ball with another a ball socket inside it, very simple. This was one of my earlier changes to the design after I did the original sketch
I searched around the web to see if anybody else had the same idea and found that while it seems uncommon, some notable robots such as the Asimo
have done the same thing, though in a slightly different way. I note, however, that no ball-jointed dolls I could find have this.
This is done in Sculpey III and resting on the blue lid to the bowl I've been keeping my little sculptures in. The actual robot will be too big, but most of his parts should fit. I'll move this into my scraps when I get more done.