Pencil on paper; sketchbook pages.
Several things going on here: I'm learning how to use cross-hatching to create tone and volume, and I'm using two grades of pencil to add more variety to the marks. (The pencils are HB and 2B -- or it might be a 4B; it's so old and well-used that the legend has long ago worn off.) In the last picture, I created the background with cross-hatching, and then softened it by lifting away parts with a putty rubber.
