So some late-night Mama magic happened.
Based loosely on a Lotta Jansdotter's diaper bag pattern, I used scrap denim I had on hand to create the messenger style bag. I sized the bag so that The Dangerous Book for Boys could fit in the main pocket, with room to spare. With some creative stitching a sample fabric, that had two coordinating fabric swatches attached, became the outside pocket with two little bonus pockets -- perfect for the compass, magnifying glass, pocket knife and found treasures!
A button and ribbon to hold it closed and, voila, there was an adventurer's bag to encourage my growing son to pack up some supplies and seek out adventures in his expanding world!