This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
Procure a large cigar box, of the square variety, and three ordinary drinking glasses with very thin walls and of different sizes, and place them in the box, as follows: Space them evenly, and drive three brads close to the circumference of each glass bottom, so that the glasses will have to be forced in between them. To prevent the glasses from touching the wood place a one-cent piece under each one.
A fourth glass is used, but from this the bottom must be removed. This can be done by saturating a string, or piece of yarn, in kerosene oil, wrapping it once around the glass near the bottom, then lighting it and allowing the string to burn out. The glass is then quickly dropped into cold water, which will remove the bottom.
A hole is cut in the cover of the box to receive the bottomless glass from the upper side, so that its lower edge will be flush with the under surface. Cut a slot, 3 in. long and 1/8in. wide, in the cover near the back side.
To use, close the cover and at a distance of about 1/2in. from the glass in the cover, or mouthpiece, sing into it. The glasses will impart to the voice a peculiar tone delightful to hear. - Contributed by J. B. Murphy, Plainfield, New Jersey.