Now cut some long triangular cardboard wedges. Start by bending these as close to the curve of the dome frame as you can. Start by gluing the wedges to the frame first with the hot glue gun, then working your way gradually to the middle of each frame section. There will be a lot of trimming and adjusting involved so take your time. Getting the curve of the dome right will make finishing the helmet much easier. After the dome is filled in smear all the seams on the outside of the helmet with white glue. You can see that I've also cut out the opening for the visor at this time. Now drop that bucket on your head and make sure it fits the way you want it to.