Plastic bag ropes

It's surprising how strong a strip of plastic bag can be. Cut it several inches wide and twist to make a rope or cord shape for tying almost anything. It won't stretch out once it's twisted and tied.

Free rope

When you cut up old clothes for rags (you do, don't you??), cut alongside the seams and keep a few on hand for lightweight rope. Depending on the material and type of seam, these can be sturdier than you might think. Tie them together for a longer rope.