This is some further refinement from http://www.thingiverse.com/thing:4126 both with and without the mandible from http://www.thingiverse.com/thing:3580, both whole and sliced in half.
In my previous attempt, I deleted all of the inside to create a solid object with all the porous and hollow parts filled in, and all external holes closed.
This time, I did the reverse, deleting all of the outside and the smaller internal features, to create simple internal volume (mostly the brain cavity). Then I subtracted the cavity from the solid object, did a small amount of further refinement, and then split it. I reduced the resolution of the mandible from http://www.thingiverse.com/thing:3580 to match the resolution of the skull then smoothed, scaled and rotated it to fit as closely as possible. I then cut off and cleaned the remains of the skull\'s original mandible and subtracted this mandible from the results.
This should give a partially hollow model that still has all the small internal details that can't be seen removed. I have uploaded (and included in the blender file) both the original cleaned skull and the one with the replacement mandible fit in. I also sliced both skulls, but only included the bottom for the second one, since the top didn\'t change.
I hope that the results will take less time to print than the previous two models.
Work on this model was done with Meshlab and blender.
The blender file is large, as it includes the original model, the inside and outside surfaces, and the split parts, each named and in their own layer.
Note that I made no attempt to center these objects. Most print processing software automatically centers it, and centering the model here makes it hard to edit the parts.
The replacement mandible is not a perfect fit, but it is close.
I\'m open to suggestion as to how to make the mandible printable (including fusing it back into the rest of the skull).
If you are building from the stl files, pick one of these sets:
wfu_cbi_skull-hollow.stl if you want one piece without a jaw
wfu_cbi_skull-hollow_jawless.stl and mandible-cleaned.stl for a one piece skull with the jaw that fits it.
wfu_cbi_skull-hollow_bot.stl and wfu_cbi_skull-hollow_top.stl for two printable pieces without a jaw
wfu_cbi_skull-hollow_jawless_bot.stl wfu_cbi_skull-hollow_top.stl and mandible-cleaned.stl for the complete printable set (but not sure if the jaw can be printed easily)