What material best for a custom amp stand

I plan on having a custom amp stand built to hold my current 250lb 2 channel amp. I will place it behind closed doors so appearance is not important. I was planning on having a metal shop create something (although I am open to other ideas). My only requirements are that it support the weight, that the platform is approximately 6 inches off of the ground, and that it doesnt vibrate. It will rest on a concrete floor. Thanks in advance for your input.
Personally, I like maple wood. It's economical, dampens vibration and should be at least 3 inches thick with isolation spikes. I believe there is a guy making these types of stands to custome specs here on Audiogon.
2"-3" thick should be no problem, check this site or Mapleshade products.

I will go with stacks of different materials to dampen different frequencies. I will use maple block + BDR cones + acrylic + whatever you can think of. Metal will ring unless you damp it well. stay away from soft compound unless you are sure it absorbs the freq you have problem with, otherwise sound will become soft usually. also play with changing the stack, using acrylic on top or below maple can sound different.
Very good info from Serri. I have heard many like maple for its sound with components vs. other woods and materials. I have heard bubinga is another favorable wood which I have drums made from. Tama made 100 "Warlord" kits from 100% bubinga for depth and warmth. They now make their Starclassic from birch/bubinga for projection and warmth. The point is even instrument manufactures constantly research different woods for sonic qualities as you will find audible in audiophile applications.
Get SYMPOSIUM stand they make wonderful amp stand. Or you can get Svelte shelf put your own pointed brass cones for lees money. Wood and Granite color the sound SYMPOSIUM does not. Remember you get what you pay for!