I recently visited Serious Eats HQ in New York, and left with this awesome bit of swag: a reusable grocery bag with the Serious Eats logo! Nice.
One problem, though: the stuff sack wasn't sewn into the bag. Since I like to stash these little bags everywhere (the car, my backpack, my bike bag, etc) the stuff sack is a necessity. Thankfully, this is easy to fix! So easy, in fact, that you're getting this Photo Instructable instead of a big pile of steps. Here's what you do:
1) Turn both bags inside out.
2) Pin side seams together, making sure the stuff sack's opening is next to the side you're sewing. (Not directly across from the seam.)
3) Sew the seams together. I used a serger because a) I have one, and b) they're super fast and easy, but a pass with a regular sewing machine would do just as well.
4) Stuff bag into your newly-attached stuff sack, and head to the grocery store with a smug smile.
5) Repeat as necessary.