I second that. I have a FG helmet as well. I didnt have a seem on mine? But i had a boat load of excess FG on the bottom. I was afraid of cutting it cuz i didnt want to crack the helmet, so i just took a rough grit and sanded it off.
Be sure to in a well ventilated area cuz FG dust isnt the best thing for ur lungs. Use one of those foam mouth pieces, if u dont have one take a hankercheif (spelling?) and wet it, then wrap it around ur mouth. Also have eye protection.
For paints I used car paints. THey come in a spray can and they worked well. If u need help on anything else just ask!