Koh uses two-dimensional photography to create holographic, three-dimensional constructions. Photographs are digitally printed on transparent film and laminated between clear plastic sheets. These sheets are then stitched together with a heat gun to form a sculptural shape. This photo sculpture has a transparent surface that reflects the images of the world, and yet reveals the emptiness of its interior space. The overlapping planes create an illusion of indefinable depth and varying imagery, depending on the viewing angle. Building-70 is a circular, building-shaped work that uses photographic images of the exteriors of worn-out buildings in Taipei. The photographs were taken in 2010.