This activity resource shows you how to make a simple plaster cast of a 3D object (we used a plastic toy duck) and then use pressed clay to make copies of the object from the plaster mould.

Plaster mould and clay reproductions

Plaster mould and clay reproductions

This activity has been designed for KS 2 and KS 3 / CfE Level 3 & 4 students, but could also be used with older students, or by lifelong learners or families.

Although casting in sculpture is usually associated with bronze or plaster (molten metal or liquid plaster is poured into a mould), the technique of making a mould in plaster and filling it with clay is one of the simplest ways of reproducing an object.

Health and safety when using plaster

Plaster can be messy with potential health and safety issues so if working with younger students, teachers should mix and pour the plaster. Older students should be supervised at all times.

Plaster dust can get into the eyes or nose so ensure that it is handled carefully and never allow students to mix plaster with their hands.


You will need:

  • plaster of Paris
  • clay
  • a 3D object to cast (use a simple object such as a plastic toy)
  • thick card or thin board (a clipboard is ideal) for the base
  • a mixing bowl or jug
  • an old wooden spoon or stick to mix the plaster
  • water
  • clay tools


Step 1. Mark the halfway point of your object

Mark the halfway point of your object with a pen. This will help you during the next step when you begin to add clay around the object.

Mark the halfway point

Mark the halfway point


Step 2. Add clay around your object

Place your object on the board and begin adding around the object with clay up to the marked halfway point.

Build clay around your object

Build clay around your object


Step 3. Build a wall around your object

To make a wall, roll a snake-like coil long enough to surround your clay base (approx 2 cm in diameter).

Attach your wall to the clay base. Your wall should be at least 1 cm taller than your object.

Make sure it is sealed with no cracks – this will prevent the liquid plaster from leaking in Step 5.

Add a clay wall

Add a clay wall


Step 4. Mix the plaster

Fill your container with 300 ml of water and carefully pour in the plaster powder until a mound forms just above the water level.

Adding plaster to the water

Adding plaster to the water

Mix the plaster and water together with a wooden spoon until it becomes a smooth consistency, like a milkshake.


Step 5. Pour the plaster into the mould

To avoid air bubbles forming, slowly and carefully pour the mixture into the mould and leave it to set.

The plaster will begin setting immediately after it has been mixed, so be prepared to pour the mixture straight away. The plaster will begin to heat up as it sets.

Plaster setting in the mould

Plaster setting in the mould


Step 6. Remove the clay and the object from the mould

Once the plaster has set, remove the clay, along with the object. Use your clay tools or sandpaper to smooth down any rough edges of the plaster mould.

Remove your object

Remove your object


Step 7. Create your copy

Press clean clay into the plaster mould to create your copy of the original 3D object.

Press clay into your mould

Press clay into your mould

Now that you have a plaster mould, you can create multiple copies of your original.

Plaster mould and clay reproductions

Plaster mould and clay reproductions

Have a go at casting other objects. Once you know the technique you can cast almost anything...!


What will you do with your multiple objects?

Once fired or hardened, use your clay multiples to make a sculpture by attaching them together.

Explore different formations and see what happens!

The Lark Ascending

The Lark Ascending

Maurice Lambert (1901–1964)

Or you could arrange them on a table or on the floor to form an installation.

Untitled (Nine Tables)

Untitled (Nine Tables) 1998

Rachel Whiteread (b.1963)




Cast an object in the round

In this activity, we cast half an object – effectively creating a relief sculpture.

To cast an object in a round, a mould in two or more sections would be required. Use the technique outlined in this activity resource to make plaster moulds of each side of your object – and then join the clay sections together after casting.


Cast a plaster sculpture

In this activity, we made a mould from plaster and pressed clay into it.

You could also make your mould from clay and use plaster to cast from it. The Art UK activity 'Cast a simple sculpture' provides ideas and instructions for doing this. It was designed for KS 2 students but could be adapted for older age groups.

Explore the activity


Using silicone for a mould

Many contemporary artists use silicone to make moulds as it allows for finer details. Silicone is safe for students to use but is more expensive than clay or plaster.

To find out more about using silicone to reproduce 3D objects, explore this Tate resource:

How to cast like Rachel Whiteread

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