This slightly ridiculous project was made for my brother and his wife as an engagement present. Like many young couples, mustaches played an important role in their courtship.
The mirror is a one way mirror, covering a set of six clear acrylic plates. Each plate is engraved with a different mustache pattern and lit from the side with LEDs. Total internal reflection traps most of the light inside the plate until it reaches an engraved edge, causing it to glow brightly. The sides of the plates are covered in foil tape to further minimize light leakage.
Each turn of the knob lights up a different mustache pattern, which shines through the mirror. A 555 timer circuit switches the lights off after 30 seconds.