Get an old portrait painting, or have an art student paint up a quickie. Buy a set of fake eyes (see Chapter 7). Make a pivoting device and attach it to a motor (like the type used in inexpensive motorized animated Christmas decorations). Then, cut out the portrait eyes and mount this device behind the painting so the eyes seem to slowly shift back and fourth. You can position fixed eyes as pictured.
An additional approach is to have the portrait silk screened onto a lightweight fabric or glass, and then illuminate a hideous face from behind the portrait. Alternatively, project a changing image onto a blank picture frame.