plastic rattle

Does deadener work on plastic? Is it the plastic rattling, or is it a matter of the plastic against the metal or other plastic?
What's up with this Don guy everyone is saying to buy the acoustic stuff from? Sent him an email with my order and have heard nothing back (couple weeks now), I've read a bunch of other posts and seems like it's a pattern smh. I think I'll prob just go with secondskin for my dampening stuff.

no you need something between the metal and the plastic, closed cell foam works the best.