Many years ago, speech clinicians (who are some of the most resourceful and creative people in the world!) would fashion a listening device out of an empty milk carton to assist in auditory discrimination practice. Although there are now commercial devices that are available, and milk now comes in plastic containers, listening devices can still be made inexpensively. I was teaching accent modification in China and went to a small plumbing supply shop where they sold PCV pipe. I had the owner cut a piece of pipe about three inches long and bought two elbow joints with the same size opening as the pipe to attach to each and fit them together. The total cost in China was about $2 for a very study device which was excellent in helping my students hear how they were producing sounds. The ESL program at the college where I worked actually made 200 of these devices for their majors!