“Odd-Shape Balancing,” Friend, Mar. 1990, 14
To balance something flat and odd-shaped on your finger, you must find the object’s center of gravity. To do this, tie a weight, such as a pencil or a heavy washer, to one end of a string. Hold the other end of the string to one edge of the object—letting both string and object dangle freely—and lightly mark it along the line of the string. Then repeat at a different edge. The point where the line marks intersect is the object’s center of gravity, and you can balance the object by putting your finger under it there.