Skull Study 4 – Pen and mixed media Illustration As you will have noticed Skull Study is an ongoing series of skull drawings by us. This is the 4th in the series of skull studies with the style leaning to more “fast and loose”. A term we use for when things get a little dirty and raw. This version we drew the skull almost as it were exploding. Skull Study 4 was created with fineliners, pocket brush, Indian ink, metallic paint and spray paint.