Mirrors and Lenses (Lighting)

One ancient method of lighting buildings used bronze mirrors to reflect light. Though bronze might be too rare for use in minecraft. I've often thought that reflecting and focusing light would be fun to play with, and particularly useful. I've spent quite a few hours thinking about different placement methods too. Using lenses to focus light into a beam and mirors to reflect or disperse light, many new building strategies might be unlocked. Glass and metal crafted together is a simple way to create mirrors, and the way they're put together could change the mirror's shape and type. ...It might also be interesting but fully cosmetic to add prisms and disco balls too.