Adding a filter to secure your screen is hardly unusual, but a new monitor hack actually works better by removing the built-in polarizing filter. An LCD with no polarized film simply displays white light, but popping lenses made from the film into a pair of glasses lets the wearer use the computer normally. And you thought 3D glasses looked silly. Read the full instructions for making a privacy monitor at the source below.
DIY 'privacy monitor' hides screen from prying eyes
DIY 'privacy monitor' hides screen from prying eyes/
Removing a filter from an LCD monitor shows a blank screen to anyone not wearing polarized glasses.