I have been teaching some bargain portrait workshops with no models so I was anxious to explain lighting to novices. I had access to the planes head, but after a long quest, I actually found a male wig head, that had more natural planes for instruction and planning shadow shapes, WITH EARS, at a fixtures store.
I set up a
little web album that showed how I used it.
(I used a tiny url... not sure it will work)
They are inexpensive styrofoam, but I used acrylic gesso and with a few coats and some neutral gray they worked excellently for me. They cost
me under $10 and I made each student one. Durability-wise, they are a bit delicate, but I liked the more realistic lighting effects.
Back to your originally scheduled thread.