--> Edit 2017-02-21: I added a version with break away support beams so now you can choose ''no support'' in your slicer. <--
The famous Celtic skull from Artec (3D scanners). Made hollow so you can put an LED light under it. Original: http://www.thingiverse.com/thing:29114
I hollowed out the original 3D scan made with an Artec 3D scanner and cut of the bottom. Now less material is used and you can put an LED light under it so it glows.