Pattern calls for 6.5 oz of fingering-weight yarn; yu will need more for heavier yarns (like cotton).
From pattern description: “This is a beautiful openwork lace pattern that is fairly easy to remember. You can turn this into a beautiful rectangular shawl simply by casting on additional stitches and working additional rows until it’s the length desired. A stitch multiple of 9 is required, plus 4 sts on each side for the border knit in seed stitch. ”