I bought a Paint Your Own mask from http://www.missmonster.com/

I can't paint very well, I've never had any kind of painting training and it's never been something I've done often. I can usually customize toys just fine because generally a toy surface is smooth and you can do bold solid colours and smooth gradients. But this mask is all kinds of texture and I'm not sure I did it justice. Also it photographs poorly, it's really much darker IRL.

One more shot: http://www.flickr.com/photos/28102132@N02/3704143043/