So anyway, maybe I'll make a tutorial one day about how I made this mouth rig, which is the core of the face rig. I'm really proud of it, no doubt the best facial rig Ive ever done :D It's simple, very fast, very flexible, and has a wide range of deformations. Basically, it's made with clusters. That doesn't say much though :P But this little, simple rig, represents the glorious culmination (so far) of my efforts and plans and tests... of doing a cartoon rig that would have simple/few controllers while allowing maximum expressiveness for the face (a few years ago I was building Cousteau's face rig, and I realized that adding a central cluster on his face, with a carefully painted falloff, something that would deform all his face in a simplified, cartoony way, was such an effective face rig element. That's where it all started. Well, combined with my plans of building simple rigs, from modules, stuff that would be easy to build, easy to animate, and if at all possible... cute :D ).
So here it is, one sphere and 2 more... spheres... :P Amazing! :P OK, ugly. But these are just the base rig elements.
OK, let's show a bit of deformation goodness... :P I made the controllers free to translate, rotate, scale in 3D space, which allows me to sculpt the face freely, but I could also geometry constrain them to follow some geometry underneath the skin. That would make posing faster, but take away a lot of flexibility. Or, yea, I could allow both, just like the Face Machine does. And, of course, I could add some shapes/AUs, like the ooo shape, smile, etc. But I want to keep this rig as light as possible, and force myself to freeform-sculpt shapes, and get used to working like that, since the rig is simple enough to allow easy sculpting of the face anyway.
So here is a quick, simple deformation, using the rig: