What’s the best material to use for a quiet case??

I’m trying to think what to make my new case out of, but I’m having some trouble. What is there that blocks out sound fairly well, can be made into a case, and that’s not too heavy and not very expensive. I’m thinking about using wood and plexi, but isn’t there anything else better out there?

Acoustic Foam, it's professionally used. a lot cheaper too
http://www.allaboutfoam.com/products.cgi?cart=e2X0x0n791M201M961M66n4B8b6Y&item=acoustic

also you can use old mouse pads, they help a little.

If you're referring to actual building material and not just sheet additives, materials with high air content (foam, fleece, and wood). Or materials that have dense textured surfaces.

an all wood case with deeply ducted fans would be very quiet. If you add any windows to it don't make them very large. Depending on thickness, plexi will act as a diaphram and will transmit sound.

why dont you try linning it with Dynamat-you can pick some up at your local Best Buy or Circuit City. It's not that expensive and it works pretty good.

You can't beat LPDE PERFORATED FOAM for only $00.40USD for a 36cm X 36cm square. Your "mall hardware" should have it in stock.

I am in the process of building a case out off wood (finishing touches at the moment) where I used MDF for the whole case.

I lined the whole inside with soundproofing foam (with a sort of mountaintops pattern) which i just got from my local Do It Yourself store. It works very well from the outside with the door closed you cant even hear that the computer inside is on.

It also has a 120 mm 220V Sunon fan inside abd you CAN hear that one cause it has a "whine" sound but if you use normal fans you should have yourself a very quiet case, and compared to my g/f Athlon with stock cooler it is totally quit!