The bag is made on top of a canvas base fabric using a novelty print and a solid color durable fabric such as Duck. The novelty print gives you all kinds of options for the final appearance of the bag. It could easily be made with a child's print such as Thomas the Tank Engine or Cinderella for a durable lunch bag for a child. You could also use up orphaned quilt squares to make a great bag.
Consider making this bag as a gift. Include plastic containers for a sandwich and things like fruit cocktail. Add a thermos to keep beverages cold. If you double the goodies for inside the bag, there is always a set available while one is in the dishwasher. Think how many of those plastic sandwich bags you are keeping out of the landfill... and the sandwich is a lot less likely to get squished!