Aurium posted:

Carnauba wax melts around 82-87C (180-187F). Boiling water would be a no go. Shellacs can melt anywhere between 70 and 120C (158 to 248). Unfortunately, many are on the lower end of that range, and wouldn't work.

There are plenty of foodsafe polyurethanes too, so thanks for the reminder techknight. They would meet your temperature requirements.

As far as how serious a threat bare plastic is. It honestly is hard to say. To my knowledge nobody has gotten sick from printed items, and the vast majority of unsafe additives have long been withdrawn from the market. But some moderately hazardous ones remain if there no expectation for food handling, things like fire suppresants, industrial lubricants, and the like. All of this would be on the material sheet.

For my personal use, I'd be ok with something like a cookie cutter, but not with something like a soup bowl where a hot liquid would sit in it and possibly either leech out, or get trapped in the porous structure and spoil. Even the soup bowl would probably be safe, I just wouldn't, unless I knew more about the plastic than just what kind it was.