I heard back from James, Stroked's neighbor, I gave him a copy of the link for the hinges from the Longroof Forum, and he said it's doable. Here's the conversation.
Thank you for the file! I was able to open it and it definitely looks doable! How noticeable is this part? Do you want it to be a showpiece? 3d printing will be cheap, but not very strong or nice looking. It is a very utilitarian tool. The ones you see on TV are extremely expensive. If you are not on a tight budget, I could machine them out of aluminum which would look very nice. Its all up to you. Either way, if I get permission from the grabcad guy, I can definitely make them!
I think 3D is out, the guy on the wagon forum had 2 sets 3D printed and they both broke. The hinges are noticeable ( top of the glass), I would prefer metal, what are you thinking $ wise if they were aluminum. I wouldn’t need the logo on it either, I own an Olds. There are a few others interested in some other items, check this out https://www.impalassforum.com/threads/anyone-looking-for-cnc-parts.1320043/unread
Yes, I think aluminum is the way to go. If you didn't have the top logo, I would say a pair would probably be $150. There are also initial costs like that would probably be $150, but that only happens once.
I will post this in the Longroof Forum, to see how many might be interested in a set. Anyone here not on Longroof that wants a set of hinges?