"sandwich" platform for amps

I want ot build a "sandwich" platform for my monoblock amps. I undrstand a "sandwich" approach is best, that is, maybe 3" of acoustic foam layered between either mdf or maple wood shelves. Where dos one buy acoustic foam, and what kind is best; I know it must be very dense. Thanks, larry
I use Vibrapods between two slabs of 3cm granite for my triode amp and power line conditioner in the HT. A 15x12x6"
block of polished blk granite for the PLC in the 2 channel.
GRanite by itself rings like a bell.
Mwalsdor, you can try to put small ceramic plates between your spikes and the granite. You will have to experiment. If you get the right ceramic, there will be no ringing but an amazing overall clarification of the sound. Sounds crazy, has to be heard to be believed.
Detlof>There are no spikes touching the granite. The amp footers have been replacedwith a combo of B.D.R. "ThoseThings" bases and Vibrapods. This rest on the
granite/"Vibrapod sandwich". My speakers sit on 4" granite slabs and the stock footers have beenn replaced with a combo of Poly Crystal cones that rest on 1/2" Ebony on the granite. Where do the plates fit in? MikE
Yous setup is fascinating. I've experimented with PolyCrystal cones and liked them very much, but for this particular setup, preferred the spikes and ceramic combination, which seemed to give a sort of "airy" quality to the sound. I placed the ceramic plates of about a square inch each, between the granite slab and the cones (rather than spikes) underneath the amp.
Detlof you are right I am a cook and here again would recommend baking a sandwich on your amp versus making a sandwich for your amp. In fact in your honor I am having a "detlof meatloaf" = vegitarian (or meatless, that is the part in your honor...ha ha) meatloaf on white bread with mayo and little bitty (again for you) dill pickles on side. As you are aware of my methods I repeat here for the novice amp cook. Use foil, wrap carefully, lay diretly on amp or build a platform to cook on and turn up the volume. Warm the pickles seperately. Not each pickle just seperate from the sandwich.Both should be toastee and warn in center by the time the Beach Boys finish GOOD VIBRATIONS. Cheers! PS A Bud should suit your palate and complement the "detlof meatloaf" nicely.