The process of turning the brick-stitch embroidered panel into a pouch took a few steps, but the results are, I think, worth it. The final pouch is a drawstring bag that's as large as my hand, so it will be good for a variety of small items, and even a modern cell phone if need be. Here's how I created the pouch:
With the front panel and the piece of wool for the back pinned together with their seam allowances tucked in (the right sides out), I used an overcast hand stitch (in black silk thread) to join them. Going this route allowed me to ensure that the white even weave was as tucked in as possible, and that I was following the line of the embroidery. If I had tried to do this on the inside, as is traditional, I would have had a hard time achieving a clean seam in terms of the edges of the embroidery falling in the right place. For an outside perspective, this step seems gratuitous, given what I did later to finish the edges, but I needed the edges to be cleanly joined before I could proceed.
Before moving on to creating the edge finishing, I made two casings with the wool. I didn't measure them, but they are about 1.75" tall, unfolded. I hemmed the ends, then used a running stitch to create the tubes. I used a dark red cotton thread that matched. I then pinned them in place on each side of the pouch. They are whip stitched in place with the same red thread on the outside of the pouch.
I created two long loops of a heavy cotton string (crochet cotton), tied the ends in a knot and tucked it into place in the gap between the casings. I used the matching black silk thread and created the edge finish using this method. It is a bit intense, since it's difficult to just put it down, but it adds such a great detail, and does a perfect job of hiding the earlier stitches and any white even weave that still showed.
With the exterior of the bag complete, I created the lining by back stitching the two sides of the folded linen together, then tucking it into the pouch (with seam allowances out and therefore within the pouch). I folded in the top for a clean edge and pinned it down.
I used the red thread here again, and also again used a whip stitch to fix the lining to the casings, just above my running stitches on the casings.
I used the same heavy cotton string and created a 4-loop fingerlooped band. I cut it is half, then inserted the two laces into the casings (there there is one loop on each side). This finished the pouch. I may redo this before I give it to my friend, though. They are not as clean and I'd like, or as long as they probably should be.
Overall, I'm very happy with how this turned out. The photos don't really do the color combination justice- it's hard to tell that I used a salmon pink as one of the four accent colors, since it comes out as a silvery orange in the photos. It took a fair amount of labor to complete this pouch, but I did not dislike the process, and I'm very proud to have this wonderful little bag to give to a friend!