just found out " the storm trooper used was efx helmet as a reference, except It was made symmetrical for an easier build. I guess if you have warping issues, it may come out pretty accurate and The helmet is my work from scratch, the armor is edited (a lot, it was high poly) to work better in pepakura."
so scale of the helmet was guessed.
armor could be fx I don't know any idea how i could get the scale/size for the armor ?
thank you for your help