Collect your pet food pouches as you use them. Instead of opening them across the top, use a knife to slice them open in the gusset at the bottom so this is not visible when flattened. Rinse thoroughly and let dry.
Decide on the dimensions of your purse. Mine were determined my the amount of pouches I had. I used 3 across the front, 3x3 = 6 for the back and flap, one each side, and 3 overlapping across the bottom. Sew your pieces together using zigzag stitch overlapping the seams on the edges of the pouches.
For the strap I used fabric from an old sweatshirt - turned and top-stitched for flatness. The flap is closed with stick-on velcro, and the cat food tab "clasp" is just decorative. Use a flexible glue such as E 6000 to adhere it.
And you're done! :)