I'm going to use it for herbs rather than lettuce. But it's such a wonderful idea, I can't resist trying it out. I think I'll put it onto the back side of what will be my turkey coop which borders my backyard.
Papaboid is a contractor, and is always bringing home pieces of this and that, and that includes drainage gutter from time to time. Right now I know at least 5 or 6 pcs that he has so I think i just found a use for some of it. KOOL idea.