I must begin by saying that I am not a good artist. I can easily see in my mind what I�m trying to express, but I haven�t figured out how to get my hands to move in such a way that the vision becomes a reality. So, on the rare occasions when I have spent hours and hours drawing something, I�ve needed a model to follow for at least part of it. For me, it largely becomes a matter of math, as I literally measure relative sizes of different aspects of the subject and use these ratios to determine how to move the pencil to create the image. I somehow doubt I will put forth this effort again any time soon.