More information on this project is available at http://www.creatrope.com
Some of my Halloween work is also in other instructables:
General Grievous with Mechanical Arms
Step 1: Forming The Skull
The components are glued together with hot-glue (best) or white glue (and then staple the pieces so you can work immediately). I found staples were not enough to keep the skull stable.
Step 2: Covering & Painting
I used the paper mache recipe to cover
the outside with newsprint strips, let dry, repeat on the inside to cover the fragile lattice. It's best to cover anything you want to paint eventually.
At this point I did some dino plastic surgery, cutting down and shaping the jaw.
I added brow ridges to the original design by twisting some paper, taping place over the eye areas, then paper-mache'ing over those.
I let everything dry, then covered with a thin coat of mod podge to give it some further protection.
You'll need a thickish paint to cover the newsprint. I used an acrylic that I had laying around, combining several shades of green, barely, to put some textured streaks on the skull.