Answered
n. tilcheffCorrect answer
Legend
October 3, 2020
Inside the head you have all facial features as symbols, each on its own layer.
You move them in relation to the head oval in a way that simulates parallactic displacement and three-dimensionality.
You combine this with subtle rotation of the whole head symbol on the outside so that it looks organic.
Try with something simple first.
Here is a small animation test that I've done, employing this technique:

It works and is very easy to do.
Nick - Character Designer and Animator, Flash user since 1998 | Member of the Flanimate Power Tools team - extensions for character animation
