Lay out the bag so that the two pieces of outer fabric are together, pretty to pretty, and the inner fabric is together, pretty to pretty with the inner fabric on top. Pin the fabric together, starting with the inner lining. Pin the fabric on the sides perpendicular to the edges and then place two pins perpendicular to the top edge of the inner lining. Place two pins three inches apart from each other on the bottom of the lining. This will be your guide when you’re sewing to stop and leave a three-inch gap so that you can turn the bag right-side out later. Sew all the way around the inner lining, with your sewing machine foot as a guide and making sure to back stitch at the beginning.