im pretty sure u can just cut a piece out of syntra and glue it to the cod piece. Im pretty sure thats how its done, then u may wanna put a few coatings of triple thick crystal clear spray on, it make it looks like one solid vacuuformed piece.
this was the best i could come up with, its from the mandalorin blue prints. Follow the link and click "cod" there will be a blueprint of the entire cod piece, the tear drop will be showing, u can use that if u want.
Well, in "helmet" forum, there are several ways posted. Many like to use an adhesive, while others (like me) like to use screws, bolts, or blocks. The choice is yours, really. It all depends on your skill level and how far you want to go.