I’d say I’m well on my way to creating my own Eye of Sauron
I had a burning desire to create some sort of electronics project with mini alcohol bottles (the ones you find in hotel rooms). My first instinct was to make them light up using LEDs. Since most are clear glass, light simply passes right through the bottle’s walls. However, the bottom is often curved, presenting a concave surface. If you shone an LED through the bottle’s mouth, the curved glass acted as a perfect lens to refract the light, which further focused the already-narrow beam from the LED. In effect, you could only see the LED’s full brightness by looking at the bottle’s bottom straight on.