how to make a phone for children, so that you can talk over the fence:

take two plastic cups, using a sharp instrument pierce the bottom of each, thread nylon wire or twine through, tie ends of wire to toothpick to provide support. cut small squares of masking tape, snip squares half way down centre, slide wire or string into slit, slide tape down and press down on bottom of cup. repeat for other cup. string has to be taut for this to work.