People have been casting for thousands of years, and it has become a complex process of mass-manufacturing. Lost-wax casting can be too expensive for the average hobbyist. Cheaper and faster is the method of cuttlefish bone casting. Cuttlefish bone is soft enough to impression and carve, but can withstand the high temperatures necessary for pouring molten metal. They can be found at jewelry supply stores, or even cheaper at your local pet-store. Here's an example for casting a ring into gold.
- Take two bones and rub them together to get a smooth, flush surface. It's dusty, so do it outside. Press your ring into the thickest part of the bone flat-wise, otherwise the walls will be too delicate and could rupture. Mark on the outside how the bones fit together, so you can reassemble it later.
- Carve your sprue. This is a channel for the metal to enter the mold. The material in the sprue will have to be cut off, and ground down as part of the finishing process. Its easier to pour a better mold if the sprue is large, so don't worry about making it too big, just use more metal.
- Cut thin vent channels from the ring to the surface, to allow air to escape as the metal is poured. Clean out any dust, and you're ready to attempt your pour.
- Reassemble your mold with the marks lining up. Use binding wire to hold the pieces together tightly. Clamp the mold to a secure surface, with the hole at the top, so that you can use gravity to help the metal run to the bottom.
- Before you try to melt and pour your metal, put on all your safety equipment, and practice with an empty crucible and your tongs. It can be difficult to pour, and you don't want to make mistakes with hot metal.
- Melt your gold (22K is best to work with) with a torch until it flows. You might add a bit (5%) of zinc to improve the viscosity and lower the temperature. Pour at the lowest temperature you can, just as it starts to flow.
- Let the mold cool completely. Break open your mold, and see what you have. Use a saw, grinder, and polishing files to coax your ring into shape.
Don't worry if you have to try several times to get a good pour, metal will remelt, and experimentation is half the fun!