Sorry to say there is no pattern. Our church group has been given scraps from Robert Kaufman. I make a quilt top that measures 18.5" wide and 12.5" in height. Most of the bags are based on a 3" finished quilt square of designs that I have put into EQ7 (1" finished for the small diagonally squares). I do use an interfacing that I iron on the back of quilt top. I then quilt it with no batting. I make a strap that is 1" wide by 28" (I top stitch on both sides about 1/8" from the edge) pinning it 4" from center. I then sew the lining (I use Kona Cotton) to the top, then sew the back seam. Press and top stitch around the top. Then my friend does the French seam at the bottom and dog ear the two side bottom I think 1.5". My friend does it differently but I am disable so this is easier for me with no hand sewing.
Please note that I make the handles are different for it is easier to have the two seams to be pressed on top and not on the side. Here are some of the quilt designs that I am working on and a photo that might help you thru the process.