Everybody---I read in one of the modeling magazines some time ago that the ONLY foam insulation is foam rubber. The article sead
that polystyrene, polyureathane, and any other type of foam will
vibrate at the same frequency (?) as the source. Foam rubber is the only type to use. The others will certainly help when gravity is
turned on all the way, but not while every thing is in one piece.
I know at least HiTec even gives you a little foam rubber blanket for the receiver. I don't recall if the article mentioned velcro or silicone. It was in either Model Airplane News or RCM.

Just my $0.03 worth.
BlackBart