Zen Knitting

The likelihood is that these may have been crocheted, where you chain a length of yarn as long as you need the tail to be, then crochet 3 stitches into every stitch of the chain beginning with the second chain from the hook. They may have also been knitted this way, by casting on your stitches and then knitting 3 stitches into each stitch. With an I-cord you’d need a mechanism inside it to curl it, or a means of setting or freezing the yarn into the curls, which can be done with acryllic yarn, a form and the oven.