Rattail is an extremely soft cording material perfect for knotting macrame and Kumihimo.  It is great to work with and comes in a wonderful variety of colours. It is also available in 25 m reusable bobbins as well. It will melt so you can melt the ends to prevent fraying. This spool is 1.5mm diameter cord in Copper .  Please note that due to differences in monitors etc the colour may vary slightly from the image.