I got a lot farther on the rig this weekend. I stumbled for about a day and a half while trying to figure out how to get blender to control the axial twist of a specific bone, but keep the bone's orientation.

To make a long story short, Blender simply can't do that. Whatever mathematics it uses to compute where bones are and how the constraints work just don't have the capability of determining the axial twist of a bone. In the end the only way I could figure out how to compensate for too much twisting in the upper arms and thighs was to insert a small bone that I can manually rotate on it's axis in order to tweak the "flesh" back into place if it should rotate too much. As it stands, I just apparently lucked out when I designed the mesh and it's not taking any tweaking except when the limbs are in really extreme positions (think bondage pornos).

One thing that I wish I did (which I'll do on the next doll) is work from the inside out. In this case, I rigged the hands/feet and arms/legs first, and now I'm trying to rig the torso. Well, it would have been a lot easier to do this had I rigged the squash/squish of the torso first, then rigged the limbs and used the limbs to tweak the torso rig. As it stands right now, I've got a ton of torso bones all tweaking around the limbs, and none of them are lining up correctly so that the whole torso squishes and squashes nicely. It doesn't mean I have to start completely over, of course. It just means I need to rip a chunk of the rig out and concentrate on getting the torso right, then go back and re-rig so the limbs tweak the torso in a nice, smooth fashion instead of the kludge I've got going on now.

P.S. Happy New Year!