Scott, Yes they could have make it out of nylon, and polyvinyl chloride also known as vinyl. If you put a flame to the pc and you smell chlorine, then its vinyl It also doesn't burn if you take the flame source away. If it burns with a blue flame and drips it is a polyolefin If it burns and and black particles fly in the air and you get an acrid smell it's a polystrene polymer. Nylon burns and gives a distinctive rotten odor like burning wood. .
If you've ever taken plastic and bended it you'll notice a line of a crack that's called a "Craze line". That's caused by the pressure on the active ingredients to migrate away from the bend. This is where plastics usually fail. You are in fact elongating the polymer and it doesnt return and the polymer at that point has last some of it's flexibility and strength. Constant pressure does the same thing. Sorry to burden you with all of this as I don't get the chance to talk too much about my trade anymore.Have a nice day and it was nice chatting with you. jerry