"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
Shalom Larry,
Maple would have indeed been much better, but "real" wood is getting rare here and very expensive to buy. What I did, was to build two amp stands together with and for a friend, who has a pair of 75 kilo Gryphons, using a sandwhich of mfd, felt, lead, felt, mfd. The lead we could salvage from a defunct manufacturing plant for very little money. Since one Gryphon had to be placed very close to a subwoofer, we experimented with the felt to good effect. We placed the sandwich on a welded iron substructure, which again, with spikes, was placed on a big slab of granite. Overkill probably, but now, to quote Stu_pisado ( who certainly is not one...) once again, we are happily full of shit.
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.