PET-G Thermoforming and Heat Treatment Safety

I am planning on using PET-G in a project similar to this 3D printed arm brace. https://www.instructables.com/3D-Pri...ization-Brace/ The manufacturing process involves submerging the 3D printed part into a pot of boiling water to heat the plastic to its glass transition temperature, then molding it around an object like a person's forearm so that as the part cools it accurately conforms to the arm's dimensions. After that I want to use my oven to heat treat the PET-G to improve its impact resistance. Before doing any of this, I want to ensure this process won't release any harmful vapors or carcinogens during manufacturing. I know PET-G is safe to print without ventilation and is considered food safe. However, is PET-G safe to thermoform and heat treat? Thank you for your help in advance.

you're main concern should not be vapours - there won't be any.

But unpeeling the 'cast' from the badly blistered skin of the persons arm.

For petg to be hot enough to mould that easily - I'm not sure boiling water will be sufficient and even if it isn't it would be more than hot enough to seriously blister and burn skin.

I have a pet-g sink strainer that has boiling water poured over it regularly. It hasn't deformed at all after a couple of months use.

The am cuff is typically made of PLA so the part can be molded with hot water. It is molded over plastic from with the approximate dimension of the recipients arm or just warped around a 2x4 to create a U shape. PETG is not going to work well for thermoforming as it needs a lot of heat to soften. This is why PETG is suggested for making parts that will sit out in the sun. If you want to try, do some google searches for "Thermoforming PETG" and see what is required heat wise.