I'm printing a bunch of these to give away on halloween, along with the candy. Last year I didn't buy enough candy, so three little ghosts left empty-handed (but were too well behaved to egg my door). I still feel a bit guilty about that.
This is not an easy print, unless you cut the parts in creative ways and glue the pieces. See example in cut_pieces_X.stl.
Modelled in Pixologic Sculptris.
UPDATE 2018-10-15: I added a larger, more detailed version and fused the mandible & skull. Print the whole thing (demon_skull_v2.stl) or use the pre-cut parts (demon_skull_v2_back.stl & demon_skull_v2_front.stl). The large skull in the photo is printed in 0.3 mm, 15% infill, with supports, and put together with 6 x 30 mm dowel pins.