A few modifications:

• substituted lace-weighted yarn with fingering weight.
• used 3.25mm needle to make the loop stretchy.
• cast on 128 sts in order to make a circumference of 18”.
• provisional cast-on on a waste yarn, as I don’t want another circular needles dangling around while knitting.
• lost track of how long the tube was, but keep knitting until the skein ran out. ~20 inches long.