What do you mean you don't want to buy pepakura? The program to view pep files is free so are the majority of the actual files. I personally prefer fiberglass because that aqua resin **** is way expensive. But if you are going to use fiberglass make sure you have gloves and good ventilation and/or a organic respirator.
That first helmet i did was a straight pep job. But then I realized that other materials like card board work well for special shaped parts. For the most part I just use bondo, fiberglass, fiberglass resin, card board, and plumbers epoxy.
dude thats one cool helmet