It would just be a matter of getting the seat to someone with a scanner. My daughter took an art class at her university last year and they had a complete fab lab available, along with a nice 3D scanner that they let her use. Not saying the university would be happy about cranking out 3D printed car seats, but it wouldn't have been a problem to get the scan done. After that it's a matter of finding a fabricator who can either do the whole seat at once or do it in sections that could then be joined together. My kid just transferred to another school, and the new school has a scanner. I'll just have to see if she can get someone to let her use it.
If I can get access to the scanner, I'll let you know and see if we can work something out. I'm in northern VA, btw.