Recent digital fabrication tools have enabled new form-giving using a wide range of physical materials. However, light as a first class creative material has been largely ignored within the design of our electronic objects. Our work expands the illumination design space by treating light as a physical material. We introduce a digital design tool that simulates and visualizes physical light interactions with a variety of materials for creating custom luminaires. We further develop a computational design and fabrication process for creating custom secondary optics elements (SOEs), which provides additional handles for users to physically shape and redirect light to compose, fill, and evenly diffuse planar and volumetric geometries. Through a workshop study with novice electronic designers, we show how incorporating physical techniques to shape light alters how users view the role and function of LEDs and electronics. We produce example pieces that showcase how our approach expands the electronics aesthetic and discuss how viewing light as material can engender novel, expressive artifacts. Copyright is held by the owner/author(s).