ArtMetal

I have a plasma cutter and I have no problem cutting the copper at all. My problem is what is a good supportive surface to use underneath? I can use a large grate but I would like to know if there is anything else that would be condusive to smaller more intricate scroll type work and details. I concidered substrates like vermiculite...sand...gravel...crushed ceramic tile. Any help would be greatly appreciated. Oh and is a #5 shade enough for plasma cutting?