This sketch of Donatello represents something I rarely do, which is to draw a full figure Turtle without first at least roughly penciling in the basic shapes.
I did this one at some comic show in 2000. It's kind of funny to see what cheap paper I was working on -- as you can see from the photo, the yellow of the cover of the sketch pad I was using as a drawing surface shows right through the paper I'm drawing on.
This drawing was done with a Sharpie marker, a great tool but very unforgiving, especially on cheap paper, as Sharpies tend to bleed if not handled with lightness and precision. Drawing like this makes me nervous -- it's far too easy to make a mistake, and then the whole thing is ruined. This one came out okay, I think. -- PL