Jim Kay’s favorite part of drawing is right before he makes a mark.

“The best moment is a blank sheet of paper,” he said. “Every line is a slight degradation of that ideal.”

Kay, the artist behind the illustrated editions of the Harry Potter series, works long days and often into the night in a free-standing studio in the garden of his home in Sussex, England.

His cluttered work space contains virtually every artist’s tool imaginable, and some unlikely props: metal scrapers from a dentist’s office, which he uses to add details to clay models; insect specimens; a model skeleton; and leaves, branches, seeds and feathers that he collects. He uses those motley materials to build three-dimensional models of winged dragons, elves, goblins and trolls, which he then sketches.

“The problem with fantasy books is these things don’t normally exist, so you have to create them to give them a sense of reality,” Kay said.