I cut 2" strips of fabric. Between two identical strips of denim I put a strip of patterned cotton and sewed along all the long seams. After pressing, I cut this into 2" slices. At the top and bottom of each piece I sewed another 2" strip of denim. This made each of the "cobblestone" patches.
As I am making these bags to sell, I usually make at least 5 of one particular style at a time. So I make cobblestones in lots of different colourways and mix them up for the different bags.
I used 9 of these for each side of the bag. I joined them in strips of 3, then sewed the strips together. Then I sewed the sides together round three edges.
The handles for the bags were made from 4" strips of denim. I pressed the long edges in 1/4", then folded the straps wrong sides together and sewed 1/4" in along each long edge.
I cut lining to match, and a 2" binding strip. I sewed the lining together, then put it inside the bag, wrong sides together. I pinned the handles in place then sewed the binding round the top of the bag, slip stitching the binding by hand on the inside.