How do I make a mask for a Masquerade?

I need ta make an example of a mask to present to our principle. I would like to have a Masquerade for prom. I just need to know how to make one... any suggestions?How do I make a mask for a Masquerade?
What shape? Like the oval kind with the eye holes, or the full face kind, or the half of the face with the bridge of the nose.





I had to make a mask for an presentation of Oedipus, and what I did was simply buy one of those full face mardi gras masks from Michael's Arts and Crafts (But I am sure you can get something like that from a costume store or something similar,) and covered it with plastic wrap and used it as a mold for paper mache. The plastic didn't bend well to the shape my face, so I couldn't use it, but in the end the paper mache did, and was hard enough not to rip, yet light at the same time. Perhaps you could try this. Of course, you'll want to make sure its smoothed out and paint it.