A homemade lead mould is used to make such things as sinkers for fishing or musket balls for black powder guns. A simple process uses pottery clay, though it is rather time consuming. The process of physically making the mould takes approximately 45 minutes, but set aside a few days to make your mould. The wait time for the mould to dry can take up to 72 hours depending on the humidity and temperature of the drying area.
Make a 4-inch cube from pottery clay. Find the centre of the top square of the cube. Place a clay cutting wire in the centre of the top square on the cube. Push the clay cutting wire through the 4-inch cube to create two sides 2 inches thick.
Place the two sides of the cut clay cube on a flat work surface so the cut surface is on top. Position the item for the lead mould approximately 3/4 inch from the top edge of the clay cube. Press the object approximately halfway into the clay.
Flip the opposite piece of clay over so the cut surface is facing the bottom. Line the edges up with the clay cube on the work surface. Press the clay onto the item for the lead mould. Press the two halves of the clay together until the cut surfaces are touching.
Turn the clay cube so the object for moulding is located just below the top square on the cube. Cut two marks across the seam to indicate the top of the cube and to help with mould placement.
Carefully pull the two halves of the cube apart. Remove the object from the mould. Lay the two halves of the lead mould on a flat surface so the indentations are on top.
Cut an 1/8-inch canal from the top of the indentation to the surface of the mould 3/4 inch away. This canal provides an area for the molten lead to reach the mould area.
Place the two halves of the lead mould together, making sure to line up the two marks on the top of the mould. Carefully carve a 1/2-inch wide by 3/8-inch deep circle in the clay using the canal opening as the centre. This area is used to pour the molten lead.
Set the two halves in a safe location to dry for 48 to 72 hours.
An object that is approximately one-quarter larger than the desired item is embedded into the clay. For example, a musket ball that is 1/2 inch in diameter requires a round object that is 3/4 inch round. This is due to the fact that the clay has an approximately 25-percent shrinkage rate. Hold the two halves together with a heavy duty rubber band. Make sure to match the lines and pour-pool area on top of the lead mould. Pour the molten lead into the pour-pool area until the canal is full.
A lead mould made from dried pottery clay is fragile; the sides will flake away with use.