Kumi Yamashita's series "Light and Shadow" consists of sculptures in the media of light.
In her words, "I sculpt shadow with light or sometimes light with shadow, but both function in essentially the same manner. I take objects and carve and place them in relation to a single light source. The complete artwork is therefore comprised of both the material (the solid objects) and the immaterial (the light or shadow)."
Her surprising and often clever use of light will not only delight you, but make you think as well. Link her website, and more of her works, is below.