I made a huge shawl or medium blanket out of sock yarn that was left over from other projects. The finished blocked size is 72 inches. I used a 5 mm needle and started in the centre with dpn's. When I ran out of one colour I just added another by knitting the two together for 10 stitches and after it was blocked I cut the ends off. I had 150 gm of ugly orange, green, and hot pink sock yarn that I used for a 6 stitch sideways border. It sat around for about year and when I finished a project I would just add the yarn that was left to the shawl.