Actually my gauntlet was much too small so Im planning on remaking it! and as for fiber glass. Just cut it into small squares about the size of a card *( a card you get from poker cards or any playing card) once the out side of your piece is resined and had hardened go ahead and start fiber glassing. Take some more resin and now coat the inside of your piece but only a big enough patch to place 2 or 3 of the cut up fiber glass on to. because if you cover the hole thing half will be dry by the time you get to put fiber glass on it. So just repeat that step until your finished. It gets really messy so make sure you wear proper gloves!