Abstract: Eyetracking systems that use video-based cameras to monitor the eye and scene can be made significantly smaller thanks to tiny micro-lens video cameras. Pupil detection algorithms are generally implemented in hardware, allowing for real-time eyetracking. However, it is likely that real-time eyetracking will soon be fully accomplished in software alone. This paper encourages an "open-source" approach to eyetracking by providing practical tips on building a lightweight eyetracker from commercially available micro-lens cameras and other parts. While the headgear described here can be used with any dark-pupil eyetracking controller, it also opens the door to open-source software solutions that could be developed by the eyetracking and image-processing communities. Such systems could be optimized without concern for real-time performance because the systems could be run offline.