The infinity (or Möbius) join is such a fun technique to have nailed down. It creates a project with one continuous side. It’s relatively simple once you work out the idea behind it.
1.) First, you bring the ends together as if you were going to join a normal circle. Then you face the back bumps towards each other and slip stitch through the FLO. This puts a twist in your work. This is what we want!
2.) You then work along the FLO until you reach the point where you joined and then you just keep going along the BLO. This means the first row is twice the number of stitches that you chained, plus one.
- Lion Brand Thick and Quick, Bedrock (106 yd; 97 m/170 g; 6 oz), 2-3 skeins
- Hook — M/N (9mm)
- Yarn needle
- ch – chain
- sc – single crochet
- sl st – slip stitch
4”x4”: 7 sc and 8 rows
S/M (21″ head circumference) and L (22″ head circumference)
During row 1, do not work into the back bump of the chain.
Ch 40 (42)
Row 1: Twist work, sl stitch to form Möbius circle, ch 1, sc in same stitch space, sc in each st around, sl st in top of first sc to join (81  sts)
Row 2-3: Ch 1, sc in same stitch space, sc in each st around, sl st to join (81  sts)
Cut a long tail.
Directly over the tail, pinch the twist flat and use the tail to stitch down the twist. This will help the headband lie flat on your head.
For the nerds: Wikipedia has a 3D interactive model of a Möbius strip.