Here's a simple, no-sew, tote-style shopping bag made using only some found plastic sheeting (in this case: billboard material) and duct tape (multicolor, of course)

Step 1: Prep Found Material

I modeled this after a canvas tote I use all the time, which results in a square bag. In this case, I used an 18"-square, so begin by measuring out 36"x18." Choose which side is in/out (photo shows inside).

Step 2: Make Flat Bag

I lay down the tape on both sides then flipped it to fold/seal. I folded down the top inch or so to give it a nice clean look. Then, lay down a border of tape.

Step 3: Create Bottom to Shape Bag

Reach inside the bag and flatten out a bottom, in this case a 6"-wide section. Allow the corners to fall inward and crease (not unlike gift-wrapping). I added a line of tape between the two corners to keep them place and reinforce the bottom.

Step 4: Finish Seams

Turn right-side out (in this case, the printed graphic). Reinforce seam and bottom with continuous line of tape, if desired. I liked the bright accent color.

Step 5: Add Tape Straps

Instead of using more plastic, I tried making 1" straps by folding duct tape on itself. Accidentally, I halved the length, which created an opportunity to add another and alternate colors, which I attached using the matching accent color. Finally, I lay down another thick border of tape over the straps along the inside to attach.

Step 6: Ready to Shop!

Viola! It's ready to use immediately. I tested it with some random heavy things in the studio. Then, wondered if it was waterproof (love duct tape!), so put about a gallon of water inside, and literally swung it around to see if handles would hold. Of course they did: it's duct tape, and it held water very well. Some tiny tears in the plastic leaked, but not the seams. Happy Shopping!