Hacksaw. effectively cut pipe of any thickness, and they are the best method for straight cutting PVC pipe. They also work well if you are making a large amount of small, precise cuts. Hacksaws are best used in tandem with a vise, but any type of clamp that keeps the pipe locked in place while you cut will also work.
Wrap the cotton string halfway around your PVC pipe, and teeter-totter the ends back and forth in a sawing motion. The friction of the cotton string against the PVC pipe will cut right through it. You can also loop a piece of butcher’s twine, or kite string, all the way around the PVC pipe.