Nice Work! Broken remotes, been there and done that! When I have repaired mine or when I have got new un broken remotes, I have replaced the metal rings with o-rings. It seems that when the metal ring is connected to the typical metal key ring (with or without the small length of chain they inevitably get all twisted up causing too much stress on the plastic pieces and they break. I suspect remotes with keys carried by women in their purse last significantly longer as they are less likely to get all twisted up like they do in a guys pocket.
My solution to this problem has been to replace the metal with an o-ring. since replacing them, I have never broken another remote. I have fixed several remotes that were broken already by performing a little surgery and fitting the o-ring into the plastic and then attaching the key ring to the o-ring. In instances where the remote isn't broken, I have used polyurethane o-ring material to create an oring looping it through the metal or plastic ring on the remote and then welding the o-ring material together with a soldering iron. I have one set of keys that i repaired this way over 8 years ago and i'm still using it with the same. fabricated o-ring.
Not sure how you modeled the remote, but if you can save it as a stl file I can 3d print you some from Nylon 6 and you can have some spares.
Regards
Bill