If you want to make your own cording and have never done so before, here are some basic instructions.
First, you need your fiber to be cut to approximately double the desired finished length. Layer your threads to about half the finished thickness you want.
Knot both ends and pin one end to a stable surface. You could also tape the end, but you will be exerting some force against that end, so it needs to have a strong hold to the surface to which you attach it.
Hold the other end and pull the entire length of the fibers tight. Twist the entire bundle clockwise, keeping the length of fibers tight the entire time. Twisted until the fibers barely start to buckle and twist in on themselves. This will make sense when you get to that point. If it’s twisted enough, when you release the tension of the twisted fibers and move the two ends closer together, the whole thing will start to twist in on itself.
When you have enough twist to your fibers and they have just started to buckle, find the center of the entire length and either hang a weight at the center or pinch it and start to allow it to twist in on itself from the center. If you used a weight, allow it to drop and twist everything together. When it finishes spinning and settles, your cording will be done. If you didn’t use a weight, then gently smooth the cording out between your fingers.
Knot the open end of your freshly made cording to keep the twisted sections together. I sometimes leave enough room between the end of the cord and where I placed the knot to form a tiny tassel. Then trim the tassel ends to an even length.