This is a jpeg of a project that couldn't be scanned. It's a stag-like skull mask. The medium is a wire frame covered with 'Crayola Model Magic Modeling Compound' of all things. I chose this medium because it's very light weight which is important for a wearable item such as a mask. It's also easily molded and accepts acrylic paint with good clarity.
I've used this medium for many masks with good results. The only down side is that with time, it does shrink a bit, and therefor crack, but it's easily patched and recolored.
I was trying to creative a pseudo-realistic skull image for a masked ball. A few people have mentioned that it's reminiscent of the mystics form 'the dark crystal' - this wasn't intentional, but I'm sure it was lurking somewhere in my subconscious...we can't help being affected by our experiences.