chainsaw man helmet help

ive tried making some stuff with foam before but im still pretty much a rookie.

i have foam clay and an exacto knife, ill have contact glue (and a respirator), high density 5mm EVA foam and a heat gun after im done with orders (and sandpaper probably), i have load of paint already too.

some questions:

what's the best template to use, for foam, beginner friendly?

do i really have to buy loads of elaborate stuff like pipes and 3d printers and dremels and every variety of foam, can i not just get something for cosplay on a budget??

and for anyone who's made this before, how long does it take, what are some specific tips? i feel like using heat guns etc to shape things that arent just like simple gluing, like where you have to get angles and curves, is just really difficult so any advice will be awesome