Found the helmet on thingiverse (remix link sources added) but it was non symmetrical. so I cleaned it up in tinkercad and made it a bit taller to work better as a wearable.
I scaled it to 290mm wide (max sale up for a CR-10s) and it JUST fit my massive head (actually plenty big enough just that bottom points were a tight fit)
its hollow except some selective infill where it was needed such as the top of the head where it domes over.
Printed in Sunlu PLA + Blue Print at 240c