I've used this pattern a half dozen times already. It's alot of fun to make backpacks out of seasonal material. My babies like 'em. You can use most any backpack pattern.
My purpose for this post is to let you know that I like to use fleece in between the 2 layers of fabric for the backpack. This makes it a little sturdier, yet soft. This is not the fleece you use for blankets, etc. This is usually sold on a bolt and stored with the interfacing that's sold from a bolt as well.
I had to order the buckles from Joanne's on-line, as I couldn't find it for sale anywhere in my town.