I use a centrifugal casting system. Essentially a large dynamic tub, the centrifuge is powered by a large spring, which is cocked and locked for the process of melting and casting the metal of choice. When released, it gives enormous pressure to the molten metal now flowing outward and into the vacated flask. Notice the angular structure in the middle of image number 7. This cradle serves to hold the flask and next to it is a ceramic crucible which is where the precious metals are melted and prepared for casting.