What Finnish New Year's Eve tradition uses melted tin to predict the future?

The Finnish New Year's Eve tradition of predicting the future with melted tin is called molybdomancy.

In the traditional practice, a small piece of tin is melted and poured into cold water. The resulting solid shape is examined for symbolic forms, and its shadow may be interpreted as a prediction for the coming year. A ship might suggest travel, for example, while other shapes can be connected with work, relationships, or prosperity.

The word molybdomancy comes from Greek roots associated with lead and divination. Similar metal-casting customs have existed in several European countries, but the practice became especially recognizable as a Finnish New Year ritual. In Finland it has often been called uudenvuodentina, literally New Year's tin.

Safety and environmental concerns changed the custom in the twenty-first century. Finland restricted the sale of traditional lead-containing fortune-telling tin, and safer materials such as beeswax or special wax products may be used instead. The symbolic interpretation remains the entertaining part of the ritual.