Pewter is a low temperature alloy of tin. We use modern, lead-free pewter. It is melted in a steel ladle over the fire in the coal forge.
The halves are clamped together. Then molten pewter is poured into the mold. When the mold has chilled it is opened to reveal the spoon.
Not every pour results in a perfect spoon. Skill and knowledge play a part in successful casting. The metal must be at the right temperature and free of dross. The pour needs to be smooth and uninterrupted. If the mold is not clamped tightly it leaks molten metal! These can all lead to an incomplete spoon. Sometimes the failures become interesting sculptures!