Hi Mike,
Unfortunately, this is probably the one large feature currently not supported.
At the moment, you cannot animate or paint thickness.
Collision in Carbon is very fast and very precise.
We have looked into animatable and paintable thickness before and unfortunately we have not found a solution to this problem that would not compromise stability or speed of our collision algorithms.
It is an ongoing research effort and we really would love to add this feature; just need to come up with the right solution.
The only workaround would be for Colliders where you would just animate and extrude the mesh.
Cheers,
Sebastian