for this created a simplified flat mouth mesh and 3 lattices for narrow/wide and open shapes in Blender.
> for making mesh (to act as a simple planar lip) started with a torus and made major segments 8 and minor segments 3. then removed the bottom faces and moved inner edge loop down so whole mesh was roughly flat. then subdivided all the edges 2 times.
> for making the open shape. created one lattice for the upper open shape and a second lattice for the lower open. added divisions to lattice to help make the deformation and scaled the lattice in object mode to fit the upper part of lip. then selected top vertices of lip mesh and created a vertex group so the upper lattice only modified upper vertices. then made lattice modifier and assigned lattice to the lip mesh and used the upper vertex group. then added a shapekey/blendshape to the lattice moving a single point of lattice to create open shape. repeated similar steps for the lower open shape.
> for making wide/narrow shape did something similar with the open shape but this time used just one lattice (note the deformations are a work in progress).
