Would it be possible to have take a pepakura batman cowl, mold and cast it to make a urethane cowl? I think depending how the pep fit your face, you could have the possibility of fitting really well or sagging dup to voids inside the pep. Thoughts?
The pep file would need work. You would have to pep it in paper/cardstock, reinforce it with fiberglass or some such, use body filler to ensure the right shape and symmetry, and then seal it. You would need to effectively make a finished cowl, minus the paint job. Then, provided you used a sealer that won't negatively react with your mold ingredients, your master should be able to mold it and cast successfully.