As the structure branches into finer structural members as it approaches the ceiling. When the branches touch the ceiling, the ceiling plane is punctured with a series of openings corresponding to the intersection of the branches with the purlins and rafters. These openings become light coves and slits.
Peter Crawley The illustrations are created by hand piercing 420gsm watercolour
paper with a pin and then stitching the paper with a needle and cotton thread.