Super easy! All you need to know how to do is single crochet.

 

Supplies:

Scrap yarn, just a few yarns is all that is needed.

1 hair tie

Crochet hook, sized appropriate for the yarn.

 

Place slip knot on hook.

Insert hook under hair tie, yo hook, draw up loop, yo and pull through both loops. Essentially, you are sc'ing around the hair tie.

Work as many sc's as you can fit tightly around the hair tie. Ss in first sc. You can leave as is or make it loopy.

To make loopy, *ch 10, sc in next stitch; repeat from * around. Ss in first sc and weave in ends.