Because the melting point of the plastic is around 150 degrees Celsius above boiling water, and the plastic is thin enough that almost all of the heat can be transfers to the water, the plastic will not actually melt before all the water is boiled away. Most of the damage to the plastic will be on the outside, because the inside of the plastic is direct contact with water, and even then this is supposing that you put it too close to the fire.
It’s kinda like burning a wet newspaper. The newspaper will only catch fire after all or most of the water is gone.
Anyway, the code for it is quite simple.
Just add:
[ “can_food”, -1 ],
to the list of the nontarnishable instruments in the water_clean recipe:
[
[ "pan", -1 ],
[ "pot", -1 ],
[ "coffeemaker", -1],
[ "rock_pot", -1 ],
[ "teapot", -1 ]
]
],
Or just copy the whole recipe and modify it to take a certain level of skill if you’re using a plastic bottle.
One problem that other people brought up on this a while ago was that it might be a bit overpowered, and I can understand where they’re coming from, otherwise this would have been merged a long time ago.