Best type of metal for turntable platform?


I have someone that owns a CNC machine. And machine for me a metal platform to the dimensions of 16 x 13 x 3. Ive heard aluminum is a good metal vs price for vibration reduction. Does anyone have any recommendations? Any input would help. Thanks. 
deanshias
The floor supports will do the most if you can pull that off. I couldn't so had to do the wall shelf/platform I mentioned above. Your sound will improve dramatically when you remove all the vibrations!
The best by far is SYMPOSIUM ULTRA STEALTH EDITION this will give the best sound and isolation as well.Jump on on ASAP!!
So I decided on purchasing a Townshend Seismic Platform. Then when it warms up here im going under my floor in the crawl space and going to add supports to the floor. Then I'll ask my buddy to mill the platform.