I started out making these as an "in the hoop" machine embroidery design, but found that it's just as easy to do with my regular sewing machine, and I think that I have better control over the zipper placement and any decorative stitching.
I do use my embroidery machine to quilt the fabric (2 sections, front and back) with a quilting grid embroidery design that I found on Sew Forums. I could then monogram or personalize one of the quilted pieces. I just make the bag to the size of the quilted grid. I lay the zipper down about 3/4" from the top edge and stitch close to both edges. Then, I open up the zipper and cut a slit down the middle of the fabric behind the zipper (very important, as you will turn the bag through this opening!). Attach any ribbons or decoration that will need to be caught within the edge seams, or do any decorative stitching. Make a short tab to hold a D-ring, and place this at the end of the zipper or in the top corner with the raw edges together. With the zipper open about half-way, place the back piece of quilted fabric on top of the front piece, right sides together, and sew around the entire bag, just inside the edge of the quilting grid. Trim the edges, and serge or zigzag for a neat finish. Finish cutting the slit behind the zipper and trim off the excess fabric. Reach inside and open the zipper the rest of the way and turn. You're done!
You're welcome! I forgot to tell you that I like to use a 9" zipper, although a 7" zipper will work. Lay the zipper with both ends extending beyond the edges of the bag. After you sew around the bag, you will cut the ends of the zipper off when you trim the seam.