Cotton Bag for My Knits

This is a simple project, but practical and cool. It is a bag to take my knitting projects -you can take a look at it inside the bag- anywhere and make it portably beautiful. I did not like to move my knitting around in a vulgar plastic bag!
I have been doing mends this week, and also a bunch of similar bags in white cotton to store food in the freezer, but I won't show them, they are too boring, and simply a copy of this one in several sizes, to accommodate the different meats, vegetables, fish, etc, I have to freeze.
To make this we only need two rectangles, zigzagged all around. Make a channel in the upward part doubling the fabric twice and stitching it. Then we sew it all around except for the superior channel. Finally, we pass a ribbon through the whole round twice. 
We can use both ends of the ribbon to pull the bag closed.