This is a super bad idea. Without knowing the type of plastic and its appropriate softening temperature range, you’re likely overheating the material. That results in the release of noxious and sometimes carcinogenic vapors.
Worst part about every greentext community is people taking the posts seriously. No shit melting plastic in your room with no ventilation is a bad idea.
Worst part about internet communities is people still not understanding that no matter how dumb a thing is, there is always at least one without the knowledge who will try it themselves. Not everybody has the needed education, so what harm is there in writing a comment specifically mentioning and explaining the problem.
Even knowing this information I am still considering collecting plastic and making an orb of my own