Mechanical pencil? I wondered how you got it so dark. I thought you just poured a tub of graphite in a certain area and began erasing with some almighty electric eraser. That method of yours looks very time consuming. Though using a mechanical pencil seems effective. But messy. The usage of a separate piece of paper is a good idea. :P -hasn't thought of that- xD

Cool~ I can't imagine myself doing detailed artworks since I'm pretty lazy. ^^ No wonder I rarely draw, for an artist that is..