In my anatomy course we had to do sketches of the human skeleton from front, side, and back view. He didn't specify a medium and encouraged us to try new methods. The front view is the first time I have ever done hatching, and I'm satisfied with how that came out. The side and back are both mechanical pencil.

Personally I like the back view's ribs because I managed to get the roll down fairly well, however most the other parts of the posterior view are disappointing to me.