Ink & watercolor on paper, 9 × 12″.
The reference used below is from Anatomy 360, a series of apps with 3D models that you can light and rotate. It's great for quick mock-ups of lighting situations. I mostly use the "clay" option for reference, but you can create photo effects as well.
|Drawings by Steve Ditko (finishes by Mark Moretti)|
|detail of raw scan|