This section is from the book "The Boy Mechanic Vol. 1", by Popular Mechanics Co.. Also available from Amazon: 700 Things for Boys to Do.
Many times boys would like to make their own shots and weights for athletic stunts, but do not know how to go about it to cast the metal. In making a lead sphere as shown in the illustration, it is not necessary to know the method of molding. The round lead weight for shot-putting or hammer throwing can be cast in a hollow cardboard or pressed-paper ball, sold in department and toy stores for 10 cents. Cut a 1/2-in. hole in the ball as shown in Fig. 1 and place it with the hole up in damp sand and press or tamp the sand lightly around the ball as shown in the section, Fig. 2. Cover over about 1 in. deep. A wood plug inserted in the hole will prevent any sand falling inside. When the sand is tamped in and the plug removed, it leaves a gate for the metal. Pour melted lead into the gate until it is full, then, when cool, shake it out from the sand and remove the charred paper. A file can be used to remove any rough places. The dry paper ball prevents any sputtering of the hot lead. --Contributed by W. A. Jaquythe, Richmond, Cal.
Illustration: Mold for the Lead
 
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