Thanks for the reply. That makes a lot of sense! It sounds like the main issue is economics then, and the actual engineering behind it wouldn't be too much of a problem in the future, especially given the increased quality of prints being produced. I have read the Amos Dudley story, and he actually made his aligners the traditional way using a dental model and vacuum-forming.

If the FDA approved material get's cheap enough do you think dental labs and companies will make the switch to directly 3D printed aligners? I would think that even though you are removing the thermoforming machine/plastic discs from the equation you replace it with a need to have a post-UV curing machine. All other steps of the equation seem to stay the same; oral scanning > computer processing > printing (mold or aligner) > (thermoforming or UV curing the aligner) > cutting/buffing the aligners.