I don't know why everyone uses paintballing and airsofting as examples, how many people actually use their armor for that?
What you would want to use for an alternative to resin and fiberglass depends on what your intentions are. If you're looking to ruin your suit and run around and throw your helmet into walls, you probably won't find a decent non-toxic alternative, although there is
This thread, non-toxic Aqua-Resin, which is shaping up to be a sturdy non toxic resin.
If all you really want is a cool looking helmet that will sit on a shelf and you wear around from time to time, paper mache should work fine. It isn't terribly strong, but most people won't need a helmet you can sit on. It's completely non harmful, pleasant to work with, and can be worked on pretty much anywhere you want with no need for ventilation or respirators.
I've got an old WIP thread here:
LINK
And my finished paper mache helms here:
LINK
They aren't the best lookin things, but they're dirt cheap and totally harmless. Not strong enough for trooping, but sturdy enough to sit on display and look nice.