Step A: Making Fossil Moulds
- Split balls of modelling clay in half and shape them into flat slabs slightly larger than the object you want to cast.
- Coat the object with petroleum jelly or soapy water so it won’t stick to the clay.
- Lay the object on a clay slab and push it into the clay.
- Place the other clay slab on top of the object, pushing it down around it.
- Lift off the top slab of clay and take out the object.
- Let the moulds dry.
Step B: Making Fossil Casts
- Coat the mould surfaces with petroleum jelly.
- Work additional balls of clay with hands until soft.
- Put a ball of clay into one side of the mould.
- Place the other side of the mold on top, press carefully and open.
- Remove the fossil cast of the object and let it dry.