(This will be easy if you have some prior sewing knowledge)
PS- This is my first legit instructable so I hope you all like it.
Step 1: Materials
-A canvas like fabric
-A matching solid fabric
-Basic sewing knowledge
Step 2: Cut a Rectangle
I would double check against your own yoga mat as some can be a bit wider.
Then take your rectangle and sew the longest sides together, right sides together. (Pattern in)
Step 3: Attach Piping
Make sure you cross the piping ends down so that your seam will be all pretty when you are done.
Step 4: Create Bottom
Or you can try and free hand it, just make sure it is as wide as your bag bottom.
Then put basting stitches around half the circle and then start a new set around the other half. This will make it easier to gather the base to fit in the bottom. Don't Back stitch or else you won't be able to gather the circle.
Step 5: Strap
Use your matching solid fabric and create a strap about 2" wide. Make it about one yard long. This will very depending on how long you want your strap to be. I would say that it should be at least one yard. Don.'t worry about finishing the ends on it, we will deal with it in another step. Just sew a tube that measures 2" when flipped right side out.
Step 6: Putting Together the Bottom.
You are going to gather the bottom circle so you can fit in into your tube. You are going to have to pin it. Flip your tube right side in and have your gathered bottom piece pattern in. At this point you are going to decide where you want your strap to be on your bag. I usually line mine up with the main seam of the bag. Your going to pin the strap in place so that it is inside. This is so that when you go to flip it the strap in anchored at the bottom. Pin everything in place and sew as close to the piping/your original piping stitch as you can so you get a nice seam at the end.
Once you are done sewing the bottom flip it so its right side out.
Step 7: Sewing the Drawstring
Now take your stitch ripper and you are going to stitch rip an opening on your first seam. This will open up your casing a create a spot for your ribbon to go into on the outside of your bag.
Step 8: Adding Ribbon
Step 9: Finishing the Strap
Step 10: And Your DONE
You will note that it may have a bit of room at the top if you did it with all my measurements. This is because I enjoy a bag that has some space for my yoga clothing on top.