I just bought a 10' x 100' roll to build a new room in the bsmt. Finally getting out of the 3x6 space under the stairs. It worked in a pinch, but the wife finally decided that she likes me better mellow. It was a bitch to tend any plants past the 2nd bucket. I've used it before, works great. The idea of using the cardboard pieces is essential to avoid tear outs. I used to own a print shop and I can tell you goto a commercial print shop and tell them you need some chipboard cut into 1inch squares. You do the math, most chipboard comes in 23x35 inch sheets, it's the stuff that is on the back of tablets. There is one layer with no corrigation between thin layers of brown paper. Unlike cardboard it does not compress and get loose and torn. And is only a few dollars to buy and have cut. Then duct tape. Peace & be kind.