As far as I know he draws by hand, scans the images and cleans up in Photoshop (or similar). Since Time is mostly a static background with actors I guess he use

As far as I know he draws by hand, scans the images and cleans up in Photoshop (or similar). Since Time is mostly a static background with actors I guess he uses the same technique as stop-motion animators by drawing the background and foreground on different cels (or maybe just compositing afterwards). Or lots of copies of the background to draw the foreground into.