Use strips of duct tape to seal the fabric - half on, half off. As we have done with many purses and bags.
Flip the entire piece over and seal the back.
Trim any excess.
You should now have an envelope shape. Take one of your corners and fold it in (creating a pouch). Seal this triangle down with a piece of same color duct tape. I prefer to seal on the bottom of the bag.
Fold in the opposite corner and seal in the same manner. You can use extra tape here to make sure the bottom is super secure.
In folding in the corners you will have exposed a sticky seam inside your bag. Use two strips of tape to cover up that exposed sticky part.
You can fold the top of the strip over the edge of the bag..
Now to create a more "puckered" face for your animal purse, pinch each side slightly inward and seal off with some small strips of duct tape.
Repeat Step 9 on the opposite side. You should now have a nice and evenly puckered pouch. Your purse is essentially complete. The only thing left to do is add a strap.
I am creating a strap that is 24inches long. Lay a 24" piece of tape sticky side up on your work surface. Fold it over 1/3 the way up onto itself. If you have not made a strap before you can see my tutorial here. (Tip: it may be easier for you to create the strap out of two shorter pieces)
Fold the remaining 1/3 of the piece up to seal the strap. Trim off any rough edges. Fold the strap in half and use your X-Acto knife to make a tiny slit about 1-inch from each end of the strap. (This is where the wire brads will attach to the purse base)
Carefully (please watch your fingers!) create two slits on either side of your pouch by holding the pinch and poking your X-Acto knife through.
Take your wire brads and feed them through the straps and the purse base.
Open up the brads on both sides and using some extra duct tape, cover the brad.