Lumi is a platform for the design of expressive light behaviors, used to explore the interaction of consumer products during the design process. The Lumi system consists of a series of tri-color LED lights arranged in a ring and embedded within a portable object so that the diffused light glows through the surface. It was created to easily allow any combination of light pattern (color, intensity and speed) to be easily crafted, displayed and tested in order to determine the light’s ability to communicate an intended emotional message. We used Adobe Flash timeline animations of colored circles as a way to specify light patterns in order to make the system as accessible as possible to designers who may not be familiar with coding or electronics. Though the system is intended to be flexible enough to be used with a variety of sensor inputs, this first iteration uses RFID tags as a trigger to initiate behaviors or switch between different patterns.