This is just a resize and re-slice of the excellent shoretrooper helmet by Jace1969 (or Seankfields, I'm not sure-- I don't see the original by Seankfields on Thingiverse). It perfectly fits my 10-year-old son now that it's 85% of the original. Assembly is much easier, too.
The part count has decreased from over 20 to only 10, and it can print on a mere 4 print beds, each only 200mm x 200mm. To achieve this, you will need to use supports and waste a TON of plastic for supports. Each of the dome halves took around 24 hours to print for that reason. It made assembly afterward a breeze, though. I used Barge cement, YMMV.
Print Face_LR on 1st bed
Print Part_4_of_4 on 2nd bed
Print Part_2_of_4 and its mirror image on 3rd bed
Print Part_3_of_4 and its mirror image on 4th bed