One nice thing about sewing is the option of creating that particular thing that you have in mind but can't find. In this case, it was a bag for Peter. Understand, Peter takes his bags seriously. A strong believer in the right tool for the right job, he's on something of a lifelong quest when it comes to finding just the right pack for each of life's gear-carrying situations.
What he's been wanting is a waist pack to wear when he's out on his bike, with just enough space for a spare tube and the tools he carries. After trying this pack and deciding it was still overkill, he finally came up with this highly elaborate pattern for me (note the special, high-tech pattern paper):