When you say glue and mess how thick is it? if you can throw a picture up before next week that would be good. If your helmet is all constructed then you are good to go to fiber the inside, as for the visor section I would cut it after the fiber glass had been applied and hardened, reason being is the shape is being held together with the card still in it, so when its all solid and you finally cut it out the helmet will hardly change shape,
Don't go to mad with the fiber glass as its quite tough to sand and will bulk out the inside of the helmet with only a couple of layers so keep it smooth and flat be prepared to throw away a few brushes in the process! also do not fiber all the way up to where the visor will sit other wise you wont have a flush surface for it to go against, try to leave a flat smooth edge about 10mm all the way round (depending on what visor you have) so that it will be flush, does that make sense?
paint on some resin first, lay down some sheets of pre cut fiber glass into position let it soak for a few seconds and then apply a coat of resin over the top, you will get a lot of fibers pull off when you brush it on dont worry about that you can remove them after. You will only have a few minuets to use the resin before it goes hard (again depending on how you mix it) so plan your moves before you go at it.
