Here is my "how to" for the Stash and Dash Backpack. Let me know if you need help.
1/2 yard fabric for outside
1/2 yard fabric for lining
1/3 yard for outside pocket
1/2 yard for straps
Sorry, forgot to put fabric for straps in the picture. You'll see it later on.
With outside and lining fabric right sides together and folded in half. Trim to 20 inches from salvage end. You will be cutting through 4 layers. Turn and line up the side you just cut with bottom of your mat. Shore up one side so you have a nice clean edge. Trim the other side so fabric measures 17 1/2 inches wide. You should have 2 pieces of fabric 40 inches by 17 1/2 inches.
Cut pocket fabric 19 inches long by 10 ½ inches wide. With right sides together, fold long side to make a pocket 9 ½ inches by 10 ½ inches. Sew around all sides leaving a small opening on one side for turning. Turn and iron. Top stitch close to the top edge of the pocket. Fold outside fabric in half. Measure up 4 inches and center pocket on outside fabric. Pin and sew. Pin only to the top of the folded outside fabric.
After you sew the pocket on, match up the lining and the outside fabric. With right sides together, pin and sew leaving a small opening for turning.
After stitching, turn so right sides are now facing out. Carefully opening up seams along sides, iron.
Fold down each short side 1 1/2 inches to the lining side and pin. Sew close to the inside edge making a tube along each short side.
Fold bag in half with outside fabric on the inside. Starting past the openings of the casing you just made, sew down each long side. Turn to the outside and iron.
Your main backpack is finished. Now on to the straps.
Cut 4 strips 2 ½ inches wide and from salvage to salvage or WOF (width of fabric). Sew all the strips together to make one long strip. Fold wrong sides together and iron. To measure, lay strip on one corner of bag , up to top and over to the other side and back again. Cut two pieces this size.
Back to ironing.
Open it up and fold from each raw edge, inside to the fold. Iron and repeat on the other side.
Then fold in half again and iron. Top stitch close to the open edge.
Pin one end onto the bottom corner of your bag. With a safety pin attached to the other end, thread through the casing. Start at one opening, go around to the other side and thread through the other casing coming out on the same side as you started. Pin both ends together at the bottom. Repeat with the other strap on the other side.
I messed up here. Sew the ends of the straps down on the opposite side from the pocket. Fold raw ends under and sew onto corner of bag. Repeat for both straps.
That's it, you are done. Pull the straps and it cinches up the top.