there are a lot of ways to make a batman cowl,
to keeps things short it all matters on a few things:
Budget,
what are your skills,
what materials can you get.
what kind of model (wearable, display etc..)
I'd browse this forum some more there are a couple of faom builds which look good, are wearable and are not so expensive to make. there should be a pep file around here aswell if you want to try that angle.