The screen used ones were not latex, if they were you would see flexing and possibly warping when turning their heads depending on the actors head size, similar to how the original Halloween mask was used in Halloween 2 but looks completely different because dick warlock had a fat head. I'm not sure if they were resin or how thick, but they were 3D printed, there's a video showing the process. The one Heath removes was a silicone copy made specifically so it would look like a cheap latex mask and not have a hard stiff look, silicone was used becauseit forms to the face and half mask versions can be removed and keep its shape, latex over time if not stuffed and stored properly will not keep its shape. Here is that silicone mask, and the link to the 'making of the masks' showing the 3D printer drilling them from solid blocks of resin or maybe thick pvc, but definitely not latex or there wouldn't be any files as the would have been sculpted by hand. As far as I knew, there has never been any files 'found' or 3d prints of them. You can easily tell by simply looking at the various shapes, mouth droop, ears, cheek and edge smoothness, and other small details. Or, take a photo of one that is claimed to be a scan of the hero mask, and overlay it over the hero mask and change how opaque it is and if they don't line up exactly, which they should if they were from the same files, then its not a scan from the original. And it definitely isn't the Chinese knockoffs, the mouth is waaay off.
