After careful consideration, Tob Beg's original 3D model, as great as it is, would not do the trick in its lower part for stop mo animation purpose. Even without the teeth, I could not find a way to convincingly model the mouth within its model. I took the decision to remove the lower part of his model, and to remodel a jaw/chin that would give me a little more breathing space for modeling my replacement mouth set.
10 units of this rather unimpressive piece of molded resin has were cast after an original jaw-chin shape that I did in clay to complement the now mutilated model shown in pic 1. Having 10 identical pieces like this will allow me (I hope) to make all my replacement mouth on the same baseline. If I am molding each replacement mouth separately, I am afraid that the shape will change too much from one shot to another while Manny's speaking, making the animation very jerky. OK, it might still be jerky in the end, but at least I made an effort to avoid it!
I am using SuperSculpey Firm. Not my choice, but because this is the only pro clay that I can find around. It does the trick, however. I simply roll a piece of Super Scupey flat so has to get a skin of about 1mm think.
That skin is used to wrap the jaw piece around.
It's really like wrapping a gift. The extra material is cut away with the hobby knife.
This outer-skin made of Sculpey will be our sculpting surface. Being one millimeter thick we can choose to either sculpt-in the existing layer, as shown above for the teeth...
... or add material on the skin to add details, such as shown above. No it's not a Mexican mustache, it's the beginning of the surrounding lips.
Now you see what I mean. I could have left the lips protubing like this, giving it a comical effect reminiscent of the animation Aardman Animations (Wallace & Grommit, Chicken run)
But instead I have opted for sinking the lips into the skin as shown above... hoping not to make a too wide departure from the original Manny, who, after all, had pretty flat mouth features!