I printed the parts on card stock and put the mask together with hot glue. I changed the overall shape after getting it together (dropped the lower lip and chin, removed the sides). I did a couple layers of paper mache, then a couple layers of wood glue + plaster of paris, then many, many, many layers of filling primer paint with sanding between each step.
Some dumb battery powered LED lights along the edges and above the eyes provide the dumb light effect.
I hot glued some strips of hook-and-loop to the sides, with the hook-side out so that it can grab on to my balaclava.