I'm not sure what you're planning, but I think you could use eggcrate panels, man. You can get them up to a 1/2-3/4 inch thick, and they're reletively inexpensive. Home Depot, and sometimes Lowe's carries them, and they run about $11.00 for a 2' x 4' sheet.

They are normaly used for lighting, but they make great shelves, too. I'm gonna use them to help drainage, and as a shelf for my hidden Carbon filter, lol!

:thumbsup:

This is what they look like.. ..just so you get an idea, cool?

http://www.louversintl.com/products/..._eggcrate.html