Cuttlefish bone casting is an ancient technique that involves pouring molten metal directly into the carved bone. Sand casting is also very historic: it is the process of pouring metal into a carved cavity of sand.
Nine two five. The three numbers attached to a specific alloy: sterling silver. 92.5% fine silver, and 7.5% copper and other alloys. I love the versatility of sterling: it is forgiving to cast and willing to work-harden under a planishing hammer.