Step 1: Lay out a plastic bag.
Lay out a plastic bag, tucking in the side seams and smoothing the bag flat. It doesn't have to be perfect.
Step 2: Cut off very bottom of bag with scissors.
Step 4: Cut folded bag into strips.
Keep it simple.
Step 5: Unfold one of the cut strips and begin joining.
Grab a second cut strip and unfold it. Loop it around your thumb and index finger and hold the rest of it in your fist.
Step 6: Continued bag joining.
While maintaining the loop in your right hand, grasp the strip from your left hand and pull it partially through the loop in your right hand. (The 2nd & 3rd pics in this step.)