On request by members of c3po-builder’s club. Here is a quick sketch of the plastic ABS helmet assembly method I used to secure the two helmet halves for wearing. The registration tabs are “sculpted” in fiberglass, and are used to keep the two halves together perfectly once the head antenna and neck bolts are correctly screwed into position. Please note that the head antenna bolt goes through the ‘hook’ on top of the helmet front.
For the fiberglass helmet, the easiest way will be to implement the head antenna-screwing method, together with the neck bolts (This was done for AD in the movies, and this can be seen in some of the behind-the-scenes photos). But the registration tabs are already molded into the helmet, so those are not necessary.