Prism99

I looked at the website and like the rug. You are going for a frayed look??? The website author used cotton interlock, which is a stretchy knit cotton that does not fray at all along cut edges. Quilting cottons are woven, so they will fray. I would think it is much easier to use stretchy fabrics for this quilt, as it takes a lot of manipulation to get the fabric through the holes and tied into a knot. If you want a frayed look, I would not count on cheap fabrics fraying more than LQS fabric. I think the deciding factor (aside from fraying and ease of manipulation) would probably be cost. The author on the website used 11 yards of cotton interlock (which is usually sold in 60" widths, I believe) to make a 4'x6' rug. Made with quilting cottons, I think the same size rug would require at least 16 yards of fabric. My local LQS sells most quilting fabric for $12/yard which would make this rug very expensive.

Edit: I just checked on fabric.com and their cotton interlock fabric is indeed 60" wide (about $9/yard).