What is a sketch cover? Sketch covers are designed so that the artist (or any artist for that matter) can draw or paint a unique, personalized cover on each copy. Sketch covers are actually printed on Strathmore 400 Series Bristol –the same stock as our pre-lined artboards. The bristol cover allows the artist to pencil — and even ink — on the cover exactly as they would on an art board. It IS an artboard, after all. I tend to do Humorous or sexy covers something off-beat from what the book is, to make it memorable for the person buying from me.