The 3D Aspect of Hand-Drawn Animation

People often distinguish hand-drawn animation from CG animation by referring to them as "2D" and "3D." This distinction leads naturally to the thought that hand-drawn animation is primarily concerned with shapes, silhouettes, and other flat graphic qualities.

But really during the Golden Age of Animation in the 1930s and '40s, animators had to be very aware of 3D forms. When Disney animator T. Hee developed the caricatures for the short "Mother Goose Goes Hollywood," he thought of them in terms of dimensional volumes, based on spheroids, and seen from different angles.

The mouth on the Katherine Hepburn model took a lot of special care because it's not just a flat downward crescent; it also goes back into the head, and he notes how far back it should go as seen in profile. 

Here's the Silly Symphony from 1938, where you can see the caricatures in action. Look for Katherine Hepburn, The Marx Brothers, W. C. Fields, Charles Laughton, Spencer Tracy, Laurel and Hardy, Edward G. Robinson, Clark Gable, Fred Astaire, Greta Garbo, Fats Waller and Cab Calloway. Because of the racial and ethnic stereotypes, the film isn't often seen these days.

The model sheets are courtesy Bill Peckman and Michael Sporn.
Mother Goose Goes to Hollywood (1938) Thanks, Christopher