Knit on 13 st in purple. Kfb all with purple on one side and blue on the other. Transfer onto two circulars. In purple, p around, turn. In blue, k around, turn, p around, turn. Continue, alternating colors, to make a pocket open on one side. When pocket is approximately square, k2tog across in purple to close the top. Switch to scarf pattern in purple and continue until nearly at desired length. Add a second pocket. Finish with 3nbo.