I used aluminum flashing from Home depot and as I had figured, parts of it melted from the heat of the burner. It wasn't too expensive and it was easier to get then stainless. I didn't want to use galvanized since the fumes that come off when it heats up are toxic, and I didn't want mild steel since it would just rust. Even with my slightly melted heatshield it still works much better than nothing at all.