Do you have a mannequin head? If so, you could probably use that as well; I did for my Robin mask. In order to have something molded to the countours of your face that will also move/stretch with your expressions, you'll need to use liquid latex to create the mask.
I've done craft foam domino masks that were also heated then molded to a mannequin head. They laid on my face better than just using the flat craft foam as-is, since I was able to mold it around the brow, nose, and eyes of the mannequin head. It didn't move with my expressions, but it works ok.