As a note for those interested, here is kind of an explanation of the terms related to manufacturing processes discussed in this topic:
Die casting is when molten metal is injected into closed dies, which are opened after the metal has cooled.
Die forging is metal heated to a plastic, malleable state and pressed into the die. When cooled, it is removed from the die.
Die striking is when a FLAT sheet of stock metal is struck by a heavy die press, forcing the sheet metal into the die. It may use cut to shape planchetts or it may just strike pieces on a sheet which are cut later. Coins and hollowback badges and pins (tinnies) are commonly die struck.
Investment casting (AKA lost wax casting) has been around for many hundreds, if not thousands of years. Today, it is the most common form of cheap jewelry making. Do a search for investment casting patterns and you will find many thousands of wax models that can be used in the investment material. That method is simple: you take the wax model and attach a sprue (another long piece of wax from which to hang it in the investment material). You mix the investment material into a crucible (disposable), you then stick the wax model into the investment material, leaving the end of the sprue exposed. The entire crucible should then be placed in a vacum chamber to remove any air bubbles from the investment material or stuck to the wax model. When the investment material is dry, you place the crucible into a furnace, upside-down, and melt out (burn away) all the was, which runs out through the hole left by the sprue. Once the wax is gone, you proceed to pour your silver into the sprue hole to fill the mold. The silver has replaced the 'LOST WAX' and you have a perfect copy, although slightly smaller from the shrinkage of of silver as it cools. You must make your wax model slightly larger (5 to 9%, depending on the silver alloy) to get a casting of the correct measurements. It is a simple process and has been used for years. I have seen demonstrations, using antique casting equipment, where a piece of wet leather was pressed over the sprue hole, after the silver was poured. The steam created, on the hot investment material, drove the silver down into the casting cavity to better fill the cavity. Once the mold has cooled, the investment material is broken away (it is brittle after the heating) and "voila' out comes the object of the casting. A little pickling, polishing and burnishing, and a thing of beauty is finished.
