Create a sculpture from a soft medium such as clay or wax and allow it to thoroughly dry. If you are making decorative figurines for your home, you may choose to purchase unglazed clay items or wax figures.
Make a flexible mold of the sculpture by coating the entire surface of the figure with liquefied or silicon rubber. Note, there are different types of rubber used for making molds depending on the material of the original sculpture, the desired drying speed, and the temperature and humidity of your home or studio. The molding step is crucial because a poorly designed mold can distort the bronze cast or cause air bubbles. The mold needs to be created in a way that allows it to be easily removed from the original sculpture.
Create divisions or shims for the mold by placing three inch strips of firm, wax-covered paper (from paper cups) into the surface of the wet rubber. Divisions allow the mold to be made in two sections so it can be easily separated to remove the wax casting. Depending on the size of your sculpture, after the first coat is cured, add more coats by brush, allowing each coat to set until a desired thickness is reached.
Allow the rubber to dry completely. Build a protective plaster mold around each half of the rubber mold by pouring the plaster mixture into the divisions and allowing it to dry.
Paint hot liquid wax into the inside of the rubber to capture all details of the sculpture. Join the two mold halves together by pouring hot wax into the mold, swirling it around, and then pouring it out. Keep repeating until the wax thickness inside the mold is one quarter of an inch. Allow the wax to cool.
Remove the rubber inserts. A hollow wax casting of the original sculpture is now ready for molten bronze. Chase or finish the casting by repairing any imperfections. This is accomplished using hot wax and heated tools to clean damaged areas.
Pour the molten bronze into the casting. After the bronze dries, break away the mold and remove the bronze. Clean any imperfections or debris and treat the sculpture with an acrylic varnish or other chemicals and heat to give the bronze a color or patina.