This is my brain at age 23. It is only the cortex, which was extracted using freesurfer. I included the Right & Left hemispheres as separate STLs and one full cortex. The inside is not hallowed out, so you can see inner cortex, but it takes forever to print.
What is what:
downampled stl files:
3Dmari.stl (both hemispheres)
LEFTmarianne.stl (left hemisphere)
RIGHTmarianne.stl (right hemisphere)
original brain images, full resolution:
lh.pial.stl (left hemisphere)
rh.pial.st (right hemisphere)
Instructions are here:
Full disclosure: I am a neuroimager. So this might be easier for me to accomplish than for most people who cannot access an MRI easily.