As part of an insane bit of mad science in Illustrator, I created an image with the layers set up in such a way that I can basically mix, match, and further edit various character attributes like eyes, noses, etc by hiding and unhiding the right layers. It's sort of like character creation in an RPG, except a lot more manual.

This sketchbook, then, is simply the result of me testing it out by making various faces with it. It's a work in progress and I put little to no effort into their hair (obviously), but frankly, something like this could be a lifesaver for crowd scenes. Heck, it could be fun to set up tables and randomly generate the background extras in future scenes.