You will need: two pockets cut from jeans (I usually cut mine 6" or so wide and 8 inches deep; children's jeans work really well for these); two pieces of lining the same size; a zip to fit the short edge of the fabric and a piece of piping cord or similar for the strap.
Open the zip! (very important!)
It's a simple little bag; making them in batches I have found them very quick to complete. I'd love to see any you make.