Collect all your used grocery bags and organize them according to color or size so that you will be able to plan how your final purse will look based on your available resources. From here, you can pick the ones you will use for your craft project. For instance, you can use all white plastic bags or you can include a plastic bag logo as part of your purse's design.
Lay down your chosen plastic grocery bags on top of each other on your ironing board. Place a single piece of parchment paper on the top and bottom of the pile. Cover the entire surface of your plastic bags from the top and bottom using the parchment papers.
Turn on your iron and keep it in low heat. Run it over your top parchment paper. Move the iron constantly over it until the plastic layers are fused together. If your iron is too hot, wrinkles will start showing on the plastic and your layers may start to melt, shrink or shrivel. You can always check under your top parchment paper to see if everything is working fine or if you need to make any adjustment.
Allow the ironed plastic layers to cool down before removing the parchment paper. Once it is safe to hold, which will probably be about five minutes later, check if the layers are completely fused together. If not, replace the parchment paper and iron again.
Fold your fused plastic into three equal parts and then measure up to the size you want for your purse. You can use an actual purse as your guide or you can simply decide the length and width of the purse you want to make. Mark the measurements on the folded plastic. Use the lower folded part as your base. The top fold will be used for your purse's cover.
Cut your plastic based on your measurements. For your purse's cover, you may keep the shape as is or cut its sides diagonally or even make a curve shape from it, according to your preference. The cover's size may vary depending on your intended design. You may want it to have the same size as your purse's front part or make it slightly shorter.
Make 1/2-inch folds facing the same direction on the top and bottom sides of your cut plastic and then sew them accordingly. Make 1/2-inch folds in the same direction on the left and right sides of your cut plastic and then sew them as well. This will make all the sides of your plastic thicker and more secure.
Fold your plastic according to the original three folds you made prior to cutting it. This will provide the basic shape of your purse, complete with the top cover.
Sew the right and left sides of your purse.
Attach a Velcro tape in between the interior part of your purse cover and the matching front side of the purse so you can simply open and close the purse using Velcro.
Add accessories and embellishments as you please. You may add cut-outs of drawings, cloth pieces or even small braided plastic pieces to make your purse more appealing. You can also add anything from sequins to ribbons and yarns. You may also add a handle by sewing or gluing long braided plastic pieces of the same color as your purse or any other handle design that would fit your intended look for your purse.