website: https://doudulac.github.io/HeadMouse-Pi/
The HeadMouse Pi is a low cost, universal, head-tracking mouse built from a Raspberry Pi and Camera Module or ordinary webcam. Its goal is to be a viable computer access technology for me and others who lack the ability to use their hands. It offers a low-cost and no-insurance-required alternative to larger and more sophisticated devices. It requires no special apparatus to be worn (e.g. glasses or reflective dots) by the user; instead, it tracks your head in space and translates the movement into a USB mouse protocol.