Trouble printing a mask

[ssayer]

Ok, you have your 3d scan of the person's head...

1. Import it in to Blender
2. Duplicate it
3. Make the duplicate say... 97% of original size
4. Put duplicate inside of original (center it, of course)
5. Select larger head - Add Modifier - Boolean - difference
6. Delete the smaller one (you now have a hollowed out head)
7. Using Blender, make a cube that is larger than the head
8. From the back of the head, bring the cube forward until only the part of the head remains that you want to use for the mask
9. Select head - Add Modifier - Boolean - difference
10. Delete the cube

Now all that's left is the mask. If you want eye holes done, do the same Boolean - difference thing with a couple of small spheres where you want the eye holes...