save materials/support structures

If you are concerned about filament conservation, you may simply cut the helmet in half along the ridge behind the ears dordle (top and bottom). To ensure that the dome's peak prints first, just flip the top layer vertically. This way, the inside of the helmet will have almost little framework to speak of. As it is, we believe our answer will be of some value. In your kindness, please acknowledge my appreciation.

Thank you. I will try it..

If saving filament is your primary concern you could just cut the helmet in half by the ear and separate it into 2 pieces (top and bottom). Then you can flip the top one vertically so that the tip of the dome gets printed first. This way you will have barely any support structures inside the helmet. We hope our answer helps. Thank you.