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 blue. Please note that due to differences in monitors etc the colour may vary slightly from the image.