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.
Either a 12-in. length of a small curtain-rod tubing or a straight piece of small bamboo pole, cut off between the joints, can be used for the gun part of this simple device. If bamboo is used, see that it is cleaned out smoothly on the inside.
The dart used in the gun is shown at A in the illustration. It is made by threading the eye of a darning needle full of yarn, clipping all the strands off to a uniform length of about 3/4 in., and then picking out the fibers into a brushlike mass above the needle's eye. Another needle or pin can be used for fuzzing the threads. The point to observe is that the brush is of somewhat larger diameter than the bore of the gun, so that when the needle is pushed into the mouth end the brush will be compressed and make an air-tight plug.
After thus inserting the dart, hold it as shown and give a quick, sharp blast of the breath into the gun. The dart will travel with great speed and accuracy for 20 ft. or more, and stick wherever it strikes. The point being so small, it can be used in the house for shooting at a paper target pinned to the wall without injury to the plaster or woodwork. - Contributed by C. C. Fraser, Saginaw, Mich.
Ill: The Blowgun is Made of a Piece of Tubing, and the Dart of a Darning Needle