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.