Finally part three!
Once your mask is dry, you'll want to pull it off the armature and remove the inner newspaper core and the clay. The first part is pretty easy - just lift up from the underside of the mask, and the entire piece should come off the armature - clay and all. It will look a bit like this:
You should be able to grab hold of the newspaper ball and just pull it straight out. Once you've removed the paper, it is time to excavate the clay. Depending on how much clay you used, you might be able to pull back the tinfoil and remove entire sections of the sculpture at once. If not (if the clay is too thick/heavy) go back through with your sculpting tools and dig the clay out bit by bit until you can pull the rest away with the tin foil.
After this step, you're ready to decorate! You can use scissors and an exacto knife to clean up the finished mask (and to cut eye holes), and I usually sand the mask and then gesso the surface before I paint. But from here you can add anything you want - horns, hair, anything - you can even sew into (if you have a strong enough needle)!
As you can see - my masks still require a few finishing touches, but once they're complete I'll post pictures of the final products. Until then - have fun making your own!