I wish I had this pattern when my children where in school. It seemed like the store bought backpacks only lasted a couple of months and I was either mending the store bought backpack or searching for a new one in the "off season" for backpack shopping. Off season backpack shopping can be as bad as bathing suit shopping in January in the northeast!
Free Pattern to Sew a Full Sized Backpack with Pockets and Padded Straps
Debbie Colgrove, Licensed to About.com
A back pack is a great way to have a day out and still keep your hands free. Since you are the designer, you could construct this bag out of quilted fabric for an insulating quality to carry a picnic lunch. This free backpack sewing pattern creates a back pack that is approximately 17" tall by 14" wide. Large enough for your carrying needs... and as long as you don't fill it with bricks, it should be easy to carry.
The free pattern features two exterior pockets. One is a large flat pocket and the outer pocket is more of a pouch style pocket with an elastic top. You can easily add more pockets by adding another layer inside of the front and back sections and adding zipped lining pockets
Padded straps prevent a weighted backpack from cutting into your shoulders and makes it more comfortable to carry for a length of time. These padded straps use a combination of the same fabric as the body of the back pack and adjustable webbing straps.
Use quality thread
and always back-stitch
to have a strong durable backpack that you can depend on for all of your carrying needs.