Some people have been asking me how I made my Adventure Time Finn backpack. So, here's a really quick overview of the sketch I made of the pattern. I never actually made a real pattern, so this is the best I can do for now. I tried to color code it for the most part.
The way I did it was to make 2 of each of the pieces listed here for the inside and outside of the bag, except for the straps. That's because I just sewed the straps into long tubes and used them just like that. If you have questions about specific parts of it, I'll be happy to o my best to describe what I did. I hope this helps a bit!