Geoffro
How big is your head?
Comprised of 8 parts sliced to fit on an Ender or above, _also supplied are 2 cut front and back halves _(full helmet would be impossible to get on if printed in one single piece) Suggest elastic for the two halves and a piece inside up on the top. - but tight and applied/glued when the helmet is shut.
Eye holes are in the eyes, you may want to drill some smaller holes around it if the supplied view hole is insufficient.