I just took an old dress which I don't wear anymore for two reasons, a)I've had it since I was 16, and b) it's generally unflattering. But I still liked the fabric which is why I've held onto it for so long. So, I ripped the seam at the waist, and then added a wide elastic for the waistband. Super easy. And now it's a piece of clothing I'll actually wear again and won't just take up space in my closet. Here's a closer shot so you can see the waistband.