Two mirrors

HOW

1. Stand between the mirrors.
2. Observe the image formed by multiple reflections from the mirrors.
3. By trial-and-error, find the position where you get the best effect.

WHY

When viewing yourself in a mirror, you use the reflection of a wave of light from a flat surface. Two parallel mirrors reflect light back to one another. By doing so, they create the impression of an infinite number of reflections.