Here is my first short film. I made this at PDI in 1995, during a gap between commercials. I modeled and rigged the characters, did most of the animation, and developed the wobbly ink-line look.
The pigeons’ torso was a metaball surface driven by a series of spheres along a spline between the head and the body, which were both separate IK joints (so I could easily get that pigeon-head movement style without counteranimating.) The eyes, beak, legs and wings were separate objects, each of which got rendered in its own separate pass. Each layer had its vector outline traced (using a tool originally written for scanning corporate photostats for flying logos!) I processed the curves using a procedural scripting language to give them some physics and personality, and then rendered them as black ink lines with varying thickness (using a tool written by Drew Olbrich). Finally, I ran the rendered lines through some image processing filters to get the edge darkening effect, and did some iterated stochastic silhouette dilation to add random ink blotches where the lines were thickest. Simple, really! ;-)