I decided this would be the winter of yoga - I've been hitting the classes pretty hard and just got my own mat (yes, extra long). I didn't have a pattern for a yoga mat bag, but I just sewed a tube, attached a circular bottom and folded over the top for a drawstring.
My extra-long mat is heavy and I didn't want the strap to rip the fabric - this was the trickiest thing to figure out. I attached the strap close to the ends of the mat so it would pull on the ends of the bag instead of loose fabric. I also reinforced it with pieces of the strap on the inside of the bag. On the top strap I tried this technique to avoid pulling on the fabric around the strap. We'll see how it holds up.I also wanted to be able to bike with the bag, so the strap is a bit longer for an over-the-shoulder. I'm kind of pleased because the bag is super comfy.
The fabric appealed to me as kind of vintage-modern. It's Anna Maria Horner. She has lots of lovely stuff, and a fun blog.