I have not had a chance to print this yet, but I found a version of Batman's helmet from the new Batman vs. Superman movie and thought it would look cool on a Minifig. I did have to widen it a bit to fit the large Lego head inside, so it's a little off from the "authentic" scale. Also, since the eyes and mouth didn't line up right, I just filled in the eyes. It'll make it easier to paint them white like in the movie.
I added split version of the helmet to help save support material.