Depends on how do you want it finished.
The simplest one is to coat with PVA then paint. But you need to have extra clean seam otherwise it'll shown everywhere
Saw dust? never heard that , might be worth exploring. Can you elaborate?
I wanted to try paper mache method. Another
RPF member is doing it now, I might try it on my spiderman mask. It's actually newspaper coated with PVA.
I also wanted to try roof sealer method (see JFcustom thread).
I thrown these methods in someone else's thread but got no respons. Now that I have 3 masks to work with, I want to try it myself, maybe today.
I tried fiber and failed, I don't like do resin and definately not fiberglass. So I am looking for alternatives too