Here's how I like to make plarn (PLastic yARN) for The Ultimate Recycled Market Bag pattern. It works great for me, and the 1/2" (1 cm) width makes it fairly easy on the hands and arms when working it up. This is double-stranded plarn, produced by joining loops cut from plastic bags.
1. The easiest type of plastic bag to work with is the kind you get at the grocery store. It’s not very stretchy, and it’s fairly thin. Don’t use produce bags--they’re too thin.* And be sure your bags are not biodegradable.
2. Smooth the bag out flat. Fold it vertically 3 times, smoothing flat each time, until you’ve got it about 1” (2.5 cm) wide.
3. With scissors, snip off the bottom seam and the handle section at the top. Save as packing material, or recycle.
4. Starting at one end of your folded bag, snip off 1/2” (1 cm) sections. When unfolded, each will be a loop.
5. Connect the loops the way you would connect rubber bands:
a. Lay out two loops with the left loop overlapping the right one.
b. With your left hand, reach through the left loop, come up under the right loop, and grasp the overlapping right end of the left loop.
c. Then pull it back the way you came: down through the right loop and back up through the left loop, until tight--with plarn, don’t pull too tight or the loops will break.
6. Keep adding loops on the left, using the last-connected loop on the right, making sure the two sides of each loop are even. You can hold the last-made knot in your right hand to help with this.
7. Roll the connected loops into a ball, and you have plarn!
* Note: produce bags are too thin for plarn unless you use 2 loops together when you connect them.