Slat type resonator materials

I am designing a false wall slat type resonator for a large (40x20x12 foot) listening room. It will be a false wall as John has outlined elsewhere. Problem is that I live in Mexico, on the Baja, and termites are a big issue. I can frame and construct the wall without wood but am stuck on material to use for front slats. Wood is a no no. Anybody help with alternative suggestions? Thanks in Advance

You can use pretty much anything, as long as it is hard, solid, rigid. Steel plate, aluminium plate, fiber-cement board,. etc. The actual material isn't important, as long as it is fairly solid and reasonably massive. - Stuart -