This is based on the 6DOF head tracking I told you about earlier.
My intention was to create a "kit" that could be mass-produced and be effortlessly attached to any baseball cap.
The IRLEDS are attached to simple clips like shown. The housing for a triple-A battery could be attached to the top of the middle IRLED clip so that there's only two wires total, from the middle to the two sides. The IRLEDs are exposed and pointing down so that they're never obstructed even when standing up some distance from the screen.