I suspect that's true. I recently had invisalign and when I lost one they got one printed locally. the material was thicker and less precise than the original

I suspect that's true. I recently had invisalign and when I lost one they got one printed locally. the material was thicker and less precise than the original. also, of interest, my dentist said they couldn't number the trays 1,2,3,4... because that was patented. the numbers were like 1a, 1b, 2a, 2b.