Step 2: Cut Fabric for Outer Cylinder
I wanted to integrate the waistband of these jeans for my first chalk bag, so I used that as the top of my "pattern". I cut a rectangle of roughly 7" x 13" from the pants, measuring the 7" length down from the waistband, and the 13" wrapping around from front to back of the pants. This caused the rectangle to be relatively uneven because of the shaping in the side seam of the pants, which is why I show in the 3rd and 4th pictures how I made a small dart to make the piece more uniform. For a standard chalk bag, just cut a rectangle about this size from your fabric.
If you want to use more than one panel for your outer fabric that is also an option, as long as the total pieced together size is roughly 7" x 13". This is where you can get creative, so have fun!