Instrucable user redsunsoft has created a nice simple how to on making a star field ceiling.  However, his instructions aren’t for something permanent, or difficult to build, he actually used relatively cheap materials and made something that can move with him (since he’s currently renting this place).

He attached a cheap set of fiber optics he bought on eBay to a cheap particle poster board he bought at Target.  He lightly sprayed white spray paint on the front side so that it looks normal durring daylight hours, and drilled holes so the fiber optics would light up those stars at night:

All in all I think this is a pretty neat way to get a simple star field to put over a child’s bed.