So when he got his own set of scriptures for his baptism, inspiration struck. There was just enough space before the blown out knees to cut side panels for the case. I curved the corners a bit when I cut.
I loved the wolf logo on the coin pocket, so I picked it off the pants and hand sewed it onto the plainer pocket.
I searched for the right zippers and didn't find what I wanted. I had settled for using two zippers (because I couldn't buy a double-pull zipper that opened in the middle). When I started cutting, I looked at the pants and realized that the perfect zippers were already there on the zip off legs!
I used strips from the bottom of the legs to make the parts that attached to the zippers. I couldn't get long enough pieces from the pants, so there are random joins. Then I cut out a rectangle for the bottom of the bag. Before sewing, I interfaced all the pieces to stabilize the weaker points. Then I took my friend's advice and decided to line the whole thing, adding pockets on the inside.
The first step in sewing was to sew the zippers to the strips and lining, then turn it right-side out and top-stitch. After doing each side of the zipper, I zipped it all together and stay stitched the ends of the zipper and cut off the excess.
Next I enclosed the ends of this long strip by sewing them between rectangles of pant material and lining (forming the bottom of the bag). I had to fold it up a bunch to do the second edge, but it came out very nice. I top stitched those seams as well.
Before sewing the sides to this "circle", I basted the lining to the side pieces. Then I basted on handles of webbing. I then pinned like crazy to make sure the zipper circle fit the sides and sewed it all together. I could have finished the inside seams with bias tape or something similar, but instead I chose to do two lines of top stitching through the seam allowances, and then cut the seam allowances very close to the stitching. It's not perfect, but it will hold just fine.
Personally, I love how it turned out. I figure you could do this with any cargo pants if you don't have an old pair of cub scout pants laying around!