Skilled craftsmen use awls, chisels and special cutting blades to render more intricate designs. Working over a basic pattern, they cut through as many as 50 sheets of tissue paper at a time. The design, often laid out over a delicate window pane background, may include figures such as flowers, foliage, birds, angels, crosses, skeletons and historic figures, as well as words or phrases associated with specific holidays. Borders may be straight, scalloped, zig-zagged or fringed. Each design is a unique and complex work of art requiring a keen ability to envision the use of negative space.