DIY CDP Platform...

Buy a pre cut piece of granite.........

There are many choices depending on what you are trying to achieve (e.g., isolation, damping, resonance transfer). I recommend thoroughly searching the archives here and at audio asylum for more discussion on this and information. Your best solution could depend on the characteristics of the rack, table, shelf, etc. that the platform will be placed on. Some options that come to mind range from a sheet of mdf, layered mdf, an air bladder made with an inner tube placed on mdf then a floating mdf platform above the tube (sides can be added to dress it up), to a symposium clone consisting of thin aluminum sheets on the top and bottom, adhered to mdf, sandwiching a layer of presentation board in the middle (search gatorboard). If the spikes are threaded, I recommend using inserts into whatever you attach them to, so you can use them to level the cdp. Have fun.

If you can't afford granite or marble, Corian (synthetic marble countertop) works very nicely.

Go online and order a Maple cutting board," Boose Blocks ". Rock Maple 2" thick and stable. About $75. You already have the feet.Should work awesome!

Can I suggest a sand box.Picture a drawer.Make a shallow one with mitre corners for finish look.3/4" sided ply works very good.Put a bottom.Attach everything with glue and nailgun.Create one floating shelve,by cutting a slightly undersized plywood the size of the box minus 1/8" overall.
You could go with double compartments.One holds sand the second on top holding a bicycle innertube a little under inflated.Your spikes go on the bottom.
Best of luck
George

http://cls.audiogon.com/cgi-bin/cls.pl?accstwek&1153183828

These are selling at Marshalls in their kitchen department for under $30.00

Audiobugged,
Glad you noted that.
I don't mind people trying to make a profit but it is NOT a "Custom" isolation platform!!!
It is a bamboo cutting board that is super dense - think rock hard maple. It should work great as the basis for an isolation platform! Add spikes or make it part of a sandwich or in a sandbox or whatever and you just saved a load of money over the real "custom" setups!
But get the word out that you can buy them yourself at MArshall's or TJ Maxx or the Homegoods store for ~$30 like you said. They even have different sizes and thicknesses to suit your fancy.

Hello M297904,

Yes it's 2" thick solid Amber colored Bamboo. They retailed for $80.00, but Marshall's had them in their kitchen department at like $29.95. I had to hit 3 Marshall's locations to find 3 of them, and with gas prices as they are still a worthwhile venture. Since discovering the huge array of cutting boards at Marshall's about a year ago, my Wife has no issues getting me to go. I normally hover right to the kitchen dept., and have had some great cutting board finds between $12-$30. I am using some spare Audiopoints I had laying in a drawer under 2 of them. I now own more cutting boards in my 3 systems then Emeril Lagasse has in his kitchen, and yes points make a "BAM" of a huge improvement!

TJ Maxx, and Homegoods... Huh, Thanx for the Tip however I hope my Wife doesn't think I'm a Crossdresser if I start to come home and venture directly into the listening rooms with TJ Maxx bags?