What you need:
8-10 plastic grocery or shopping bags
What to do:
Cut 4-5 rectangles from an unprinted section of the bag to use as a base layer, then cut up portions of the printed area to create a design and lay them on top of the base layer, use a clear or white plastic bag to cut a rectangle that covers your whole design.
I used the cart from the shoppers logo, cut 5 of them out and placed them at different angles to create this design. Place one sheet of parchment underneath your plastic layers and place one on top, making sure all the plastic is covered by parchment.
Fuse the layers together by ironing on top of the parchment sheet with your iron set on rayon. Try to keep the iron moving at all times so that the plastic doesn't melt too much, it will have holes in it if it does. Flip the whole thing over, parchment and all, and iron that side too.
The plastic should be fuse together as one piece, it may curl up a little as it cools don't worry about that too much. Next, trim the uneven edges to make a rectangle.
Repeat the above steps to create a second side for your zipper pouch.
I used this tutorial to sew the zipper onto the plastic and finish the edges to create the pouch.