Instructables member Mike Galloway has constructed his own private planetarium: a fiber optic starfield ceiling for his newborn baby.
From Hack A Day:
"This setup involves an LED based illuminator and bundles of fiber optics. Mike first mounted the illuminator in the corner of the room at ceiling level and ran the bundles of fiber optics up into the attic. He then used a cordless dremel to drill 1/16? holes, one for each fiber in the bundle. This translates to a lot of holes! Once everything was in place, he filled the holes with glue to hold the fibers in place, and snipped off the excess from the room-side using a fingernail clipper."
Make your own. Video demonstration below.