A good headband keeps your hair back and sweat out of your eyes while you work out, and if you have some scrap fabric on hand, you can make your own, sized to fit your head - and your own sense of style.
Image from Sarah Hearts.
This project only takes about 20 minutes per headband, and if you want to make a bunch you can cut down on that time by bulk cutting fabric and sewing. You need your scrap fabric (the tutorial here uses polyester knit) cut into two pieces (14cm x 50cm and 5cm x 10cm) and a sewing machine. You could do this one by hand, but a sewing machine will make it go much faster.
If you add a strip of terry cloth or towel to the inside, you turn a thin, light headband perfect for hair styling or covering your head while you're outdoors into a sweat-absorbant one perfect for the gym.
DIY Fabric Headband [Sarah Hearts]