I made this ghost decoration for Halloween. The face is an inverted plastic mask (the inside of the mask is facing you). This creates an optical illusion that looks like the face is following you. The face is not actually moving! It will appear to look at you, no matter where you view it from.
The body is cheesecloth that was dyed with fluorescent blue paint (also used on the face). There are blacklights on either side of the inside of window to light up the ghost at night, as well as a white kaleidoscope light and white strobe lighting up the ghost from beneath. I also have a small fan blowing on the ghost to make the cheese cloth move around. The eyes are two white LEDs controlled by an Arduino board.