Facial features can easily be changed, modified or even removed. At this point, I usually work by adding wet paper clay to the bone dry base, building up layer upon layer. If a jaw line needs to be drastically altered, I use a dry wall saw to effect such a major change. The bone dry form can also be wetted down to reconstitute the plasticity of moist paper clay so that contours can be reshaped.
I'm working on a new set of 3 Japanese masks. I'll post them soon.