Seems like, in addition to that central bend, it ought to be cambered top to bottom. I can't find any side-views from the cartoon offhand, but as I recall, it has a sort of bubble appearance from the side, rather than being a straight line. It also appears to come inwards pretty significantly towards the chin, rather than just being cut into a point.
Seems like, to get that close fit from the cartoon, rather than have it as one solid piece, it might be easier to strap the visor to your head like a mask, and then just set the helmet over top.
Seems like, to get that close fit from the cartoon, rather than have it as one solid piece, it might be easier to strap the visor to your head like a mask, and then just set the helmet over top.