I have my pioneer double DIN in an adapter supplied by Crutchfield. I'm suddenly noticing a rattle between the adapter and the factory dash plastic. I put a little electrical tape on both surfaces and sure enough rattle gone.

But my temporary solution looks like S#!%! Anyone had this issue and found a good looking solution?

 

Get yourself a new adapter from Metra. They are not expensive. I have a double din pioneer with the Metra. No rattle whatsoever

 

The screws on the metal radio brackets have a bit of play in them, so you can adjust the alignment of the face of the headunit (and this the trim kit) with the dash panel. I did a bit of playing with mine until I got the alignment perfect, but never had any rattles or other noises.