It really shouldn't mold if there's nothing for the mold to feel upon.
Liquids take the shape of their container.
When cheese is still in its' liquid state, it can be poured into a mold.
A mould can be defined as a container into which liquid is poured to create a given shape. A former can be defined as having previously filled a particular role or been a particular thing.
Take a container with a rather precise scale and measure it. Place the ring inside and measure it again. The amount the water goes up is the volume of the ring. Or you could fill a container to the brim with water, with a collecting dish underneath. Put the ring in the container, which would cause some of the water to overflow. The volume of water that left the container is the volume of the ring. Or you could take a clay mold and make a mold of the ring, fill that with water and measure how much water it takes to fill the 3D mold.
mold
A mold is a form into which molten metal is poured. When the metal hardens, it takes the shape of the mold. This process is called casting.
with coal dust and resin, poured into a mold
Casting
To make a synthetic plastic, plastic pellets are melted and then poured into a mold. The mold forms the product, and then the product is cooled and the mold opened.
Water doesn't typically go bad if it is pure water. However, water can accumulate bacteria, mold and mildew. And it can react with its container. If it is free of contaminants, it will not go bad.
Mold will live as long as it's resources allow it to. Mold will thrive in dark, warm, and moist environments.
Clay can be molded by hand or by using a potters wheel to shape it. There are many techniques for shaping clay both by hand and machine. One of the common ways to mold clay is by liquefying the clay with water to make slip. The slip is then poured into molds made of plaster. The plaster absorbs the water from the clay leaving a clay wall behind in the mold in the shape of the mold. The mold is then disassembled and the resulting form, known as greenware, is slowly dried and then fired.