No sewing necessary!
You can use an iron to fuse together grocery bags into a thick sheet of plastic.
Then you can use that plastic to make a durable, waterproof, recycled messenger bag or purse.

I've seen some great instructables on different variations of the fused plastic-bag, and I thought I'd share the process I've been using.

I'll show you a purse I'm making as a birthday present. To make a messenger bag, you follow the same process but make the dimensions a bit larger.

This is a great bag for the new school year!

You'll need:

- a lot of thin, plastic grocery bags
- a few patterned or colorful bags for decoration
- 1 large trash bag, for the strap

- a clothes iron (my iron recently died, so you'll notice I'm using an old-school iron that normally gets used as a doorstop. But a normal iron is just fine)
- aluminum foil or parchment paper, to keep the iron from sticking to the plastic
- scissors
- pins, or an extra pair of hands
- soldering iron (optional)
- velcro (optional)
- Some free time, patience, and good music

Step 1: Fusing the Plastic

Your first step is to create a large, thick sheet of plastic. You'll probably want to start out by making a small practice sheet, so that you can get a feel for the process and the material.

WARNING: If at any time you see smoke or smell any fumes coming from the plastic, Stop. You're doing it very wrong. You only want to heat the plastic enough so that the layers will fuse together, and as far as I know this will not release any fumes. However, as always, you should do this in a place with decent ventilation, just in case.

I like to work on the table or the kitchen counter, with a towel covering the surface. Ironing boards are annoying to use for this because they are so narrow.

Take 2 grocery bags and cut off the handles and the seam at the bottom, so you're left with a nice rectangle. Lay the bags flat on top of each other, and sandwich them between 2 sheets of aluminum foil or parchment paper (used for cooking).

IMPORTANT: Do not touch the iron directly to the plastic. It will melt and burn and smell bad and your iron will be nasty.

You'll have to play around with the heat settings depending on how thick your sheet of plastic, but for one bag, start out on a medium or low setting. When you press down the iron, you should hear a quiet crinkling sound as the plastic contracts and fuses. If you get a lacy pattern of melted holes, the iron is too hot.

If you're using parchment paper, which is translucent, it's easy to tell where the plastic has fused and stuck to the paper.

Start out with a light pressure and don't stay in one place for too long. Wait a couple seconds for it to cool before you lift up the foil/paper, so you won't rip the melty plastic. As your sheet of plastic gets thicker, you may need to increase the heat setting on the iron.

Don't leave any air bubbles or unfused spots, or your plastic will be weak! Make sure you keep flipping the plastic over and ironing it on both sides.

Step 2: Making the Sheet of Plastic

Use plain grocery bags to build up a sheet of material. The size and thickness of the sheet you have to make depends on the type of bag you want.

The template below shows the basic shape you will have to cut out from your rectangle of plastic. You should adjust each of the dimensions depending on your preference.

If you want to make a big, sturdy messenger bag, the plastic needs to be quite thick. I can't give you an exact measurement - you'll just have to judge when it seems thick enough to keep it's shape and hold a lot of weight. You should be able to pull very hard on both ends and not have it stretch or deform.

If you're making a purse or something more light-weight, the plastic doesn't have to be quite so heavy.

This step is the most time consuming, so put on some loud music and be prepared to spend many hours ironing plastic.

Just use plain bags during this step - decorations come next.

Step 3: Adding Decoration

Here's the fun part - customizing the inside and outside of your bag with colors and patterns. Hunt around for interesting plastic bags and ask your friends if they have any they could give you.

I covered one side of the sheet (which will be the outside) with fancy gold-patterned bags from the liquor store. I also put a smiley face on what became the inside of the flap. I cut a bag into strips and put colorful stripes on my first messenger bag.

If you iron a thin piece of plastic on a very hot setting, you'll get a lacy pattern of little holes. This could be an interesting part of a design...

eclipsed has some beautiful examples of applique patterns in this slideshow: https://www.instructables.com/id/Fused_Plastic_bags_and_accessories/

Just remember to use a low heat setting and go slowly when ironing bags that have a lot of ink on them, because the ink may start to come off.

Step 4: Assembling the Bag

Now that you have a nice, pretty sheet of plastic, it's time to fold it into a bag. Figure out your final dimensions and cut the plastic to the template below, so that it looks like an unfolded pastry box.

First you fold the plastic along one of those two horizontal, dotted lines in the middle of the sheet. Overlap the two tabs so that the plastic is folded at a right angle. It doesn't matter whether that little tab goes on the inside or the outside of the long tab. You just have to fuse the two tabs together. One easy way to do this is to place the tabs on the corner of a table or a countertop, as shown below, and then fuse them together. You should use the tip of the iron to fuse the inside (white side) of the seam as well.

The iron will have to be on a pretty high setting to heat this many layers of plastic. You need to securely fuse the layers together, but don't go overboard and melt/damage the thinner surrounding plastic!

Once you've fused both corners at right angles, it's on to the next step!

Step 5: Assembling the Bag - Part 2

Next, fold the plastic along the other horizontal, dotted line, so that those two long tabs overlap.

Ironing this seam is a bit trickier, but it's the same idea. Get somebody to give you a hand, or pin the two long tabs together. Put the bag on its side so that the overlapped tabs lie flat against the table, and carefully iron the inside (white side).

If you're having trouble reaching a spot with the iron, try using a soldering iron. Just be careful not to accidentally melt holes with the tip!

Remember to iron the outside of the seam as well. The best way to do this is to take a long piece of wood, like a two-by-four, and let the end of it stick off the edge of a table. Then you put the seam over the two-by-four, so you have something to press the iron against.

Step 6: Making the Strap

You can make a good strap out of a trash bag. This is the only part of the project that's not recycled, but you really wouldn't want to wear a USED trash bag.

I like black straps, but if you're adventurous, a white or blue trash bag could make for an exciting strap. And don't worry, these straps are surprisingly comfortable.

If the trash bag has some sort of handles or ties at the top, cut them off. Then fold the bag in half lengthwise and iron it. Once it's fused completely, fold it in half lengthwise again. Keep folding in half and ironing until you're left with a long strip that's twice as wide as you want the strap to be. Cut this piece in half lengthwise, making two long strips that are each about two inches wide (for a purse, you might want the strap to be slightly narrower).

You fuse the ends of these two strips together to make a nice long strap. Make sure the ends overlap by a few inches, and that you fuse them very securely! You don't want the strap falling apart...

Then fuse the ends of the strap into the seams on each side of the bag. Figure out exactly how long the strap needs to be, then stick the strap inside the bag and fuse it to the side seam.

I've found that the weakest part of the bag is where the strap joins the top of the bag. Over time the strap may begin to rip at this point. What might help is if you don't iron the strap to the very top edge of the bag - instead leave just a little bit of space below the top.

Step 7: Finished!

Now fold down the flap. It should stay down on its own, but if you want it to close more securely use a piece of velcro or experiment with a colorful button or a magnetic closure.

And that's it - you're done! Go enjoy those compliments about your distinctive bag.