Back in '04 I was a part of the first staff hired at the then-opening Art Institute of Indianapolis. I made this drawing to give my digital painting students something to color for assignments. It was a big hit. :)
This is my own coloring. Drawn on bristol board, photographed, and outlined in Illustrator before being brought into Photoshop. It uses one diffuse color layer multiplied against everything else. It has two shadow layers (one for occlusion, and a general darkening) that the two light layers screen against.