I am in the process of making a backpack. I found (and purchased)a Coach backpack. I am not a "brand" person, but the is was at the lowest price I have ever seen. But I do not want to take this bag to Las Vegas, so I thought I would use the Coach as a pattern. I did make it about an inch wider and 2 inches taller. I am in the process of sewing it now, since we are leaving in a short time. I was concerned about safety, so my outer pockets are zippered, then the "flap" that pulls over the top, will be secured with a parachute lock. I too, had issues with the straps falling off my shoulder. The remedy was to sew the straps, butted together at the center, not spaced apart as most patterns show. I also lengthened the straps, but I made them adjustable. The outer fabric is black faux suede and the lining is hot pink batik. I always like my bags to have a bright lining. I used light weight fusable interfacing, on the crosswise grain, on the suede, and headliner fabric on the lining. Interfacing gives the suede body, but not stiff, and the headliner give the entire bag body, yet soft and bendable. (Plus it give the bag a little padding for those items inside). I added cut work embroidery on the flap to show off some of that hot pink fabric. So far, it is going together fairly easy and I hope to finish it by tomorrow. This is the third backpack I have made and am so glad this one is mine to keep, it is my favorite so far.