I recently ordered a helmet and it is very well made, however it doesn't quite fit due to the the cheek portions that protrude inward. It is a resin helmet and can be resized with a heat gun, according to the maker. However, out may be easier to use sandpaper or a dremel tool to shave down the interior. I'm just not positive of the helmet's thickness and don't want to take off too much and put a hole in it. I'm new at this (partly why I ordered the helmet along with not having the workspace to make one). My main reason for doing this is that I've been wanting a set of armor to wear for cons and watching my niece and nephews on Halloween.
Anyway any advice those here with more experience on the matter can give me is appreciated, as I'm definitely new at this. Thanks, everyone.