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.
Three of the most used draftsman's instruments are the compass, ruler and square or triangle. When it is necessary to make a rough drawing and no instruments are at hand, common and easily obtainable things can be used as substitutes.
A sheet of heavy paper folded as shown at A will serve as a ruler, and the same sheet given another fold will make the square B. If given another fold diagonally, a 45-deg. triangle is formed. A substitute compass is readily made of a short pencil and a pocket knife, as shown at C. - Contributed by Jas. J. Joyce, Olongopo, Philippine Islands.
Ill: A Compass Ruler and Square Made of Ordinary Things at Hand