Ama, Are you saying something can be technically correct but not _really_ correct? I don't seem to follow your reasoning.

There have been videos of drill press drive belts printed in ninjaflex. It is very durable material. Tens of millions? No idea. What are the requirements of the item being designed? If I want a flexible hinge for a watertight container for my phone, so I don't lose the lid, I don't need it to last tens of millions of cycles. I might never open it 1000 times.