Knot some I-cord into a headband. I like my headbands simple for everyday use; this one is thin and unobtrusive, allowing you to wear it with a variety of hair styles.

It takes much less than a ball of yarn, and this pattern is very flexible about the gauge, yarn, and needle size. I recommend using a yarn thinner than worsted, but if you prefer a thicker headband, even chunky yarn will work well with no math needed to adjust the pattern.

While there are step by step photos showing how to make the knot I used, feel free to substitute your own favorite knot.