Introduction: Making a Pencil Holder

Here's how to make a modern pencil holder! This pencil holder requires you to make two moulds and two cores out of high impact polystyrene, as well as cast it using plaster. Make sure to look at the images attached if you feel unsure about the steps. Good luck!


  • set square (30/60 or 45 degrees)
  • high impact polystyrene (HIPS) sheets
  • compass
  • pencil / eraser
  • sheets of paper
  • tape
  • protractor
  • scissors
  • glue
  • pieces of acrylic
  • box cutter knife
  • plaster
  • card
  • water
  • liquid watercolour (any colour of preference)
  • sturdy board (to place mould on)
  • small cups (reused yoghurt cups)
  • bucket
  • spatula

Step 1: Drawing Mould 1 on Paper

Draw 8 equilateral triangles on a piece of paper

  1. Draw a 60mm line.
  2. Measure 60mm on your compass.
  3. Put the point of your compass on the end point of the line (0mm point).
  4. Draw an arc from the other point of the line.
  5. Do the same with the other side (60mm point).
  6. Join the lines where the arcs meet (as shown in the images above).

Draw 4 squares on a piece of paper

  1. Draw a 60mm line.
  2. Use your set square to draw a 60mm line 90 degrees upwards as shown in the photos.
  3. Continue this until you have drawn a square.

Step 2: Drawing Mould 2 on Paper

Do the same as Step 1 but for 8 triangles and 5 squares with sides the measurement of 80mm. Refer back to Step 1 if you need more guidance.

Step 3: Drawing Core 1 on Paper

Draw 2 stars on paper

  1. Draw a circle with a diameter of 50mm.
  2. Draw a line from the centre of the circle to a point on the perimeter of the circle.
  3. Place your protractor on the line and measure a 72 degree angle.
  4. Draw a line to form the angle.
  5. Place your protractor on the line drawn, and measure another 72 degree angle, drawing a line to form it.
  6. Continue until you have 5 lines.
  7. Connect the lines in the order 4-1-3-5-2-4 (refer to the images above).
  8. Repeat this for another star.

Draw 10 rectangles on paper

  1. Draw a 180mm line.
  2. Using your set square, draw a 150mm line, which is 90 degrees from the end of the 180mm line (refer to the photos above).
  3. Continue this process to create a rectangle.
  4. Divide the length into 18mm sections using the set square.

Step 4: Drawing Core 2 on Paper

Do the same as Step 3 but for stars with a circle diameter of 70mm. The measurements for the rectangle are 250mmx160mm and each section is 25mm. Refer back to Step 3 if you need more guidance.

Step 5: Sticking Drawings on HIPS

Use minimal glue to stick the pieces of paper used onto the shiny side of sheets of HIPS.

Step 6: Cutting the Shapes

Using scissors, cut all the shapes drawn out of the HIPS. Make sure you separate the 2D shapes for each 3D shape (mould 1/2, core 1/2). Peel the paper off of the HIPS if possible.

Step 7: Making an Opening Between Moulds

An opening between the two moulds is required for them to be connected.

Take a 60mm square and place it on an 80mm square, so that two sides are aligned. Use the box cutter knife to cut along the other two sides. You should now have three pieces (refer to the images above). Place one of the squares aside (you will not need this).

Step 8: Taping Mould 1/2

Gather the pieces for mould 1 (larger cuboctahedron).

Place them in the configuration as shown by the net in the image above (shiny side up). Tape the pieces together, making sure enough tape is used so that there are no holes/gaps between the pieces. Pick up the net and curve it inwards and corresponding pieces should match up. Tape these together, covering all gaps. When this is complete, a mould should be formed (refer to the images).

Do the same for mould 2.

Step 9: Taping Core 1/2

Gather the pieces for core 1 (smaller pentagrammic prism). Follow Step 8 to tape the pieces together, using the net from the images above for guidance. Do the same for core 2.

Step 10: Joining the Two Moulds Together

Align the moulds by placing them on a flat surface with both the openings facing one another. Use tape to secure the moulds together, making sure there are no holes to prevent leakage.

Step 11: Sticking Acrylic Pieces

Use glue to stick the pieces of acrylic to the inside faces of the joint mould. Allow these to dry for around 3 hours.

Step 12: Making Them Sturdier

Cut 4 60x20mm rectangles of HIPS and stick them onto the small cuboctahedron. Do the same for the larger cuboctahedron, with 80x20mm rectangles (refer to the images above). Cut card of the same dimensions as the HIPS pieces and stick them together using tape, forming two squares. Place this onto the squares formed by the HIPS pieces added on to the cuboctahedrons as shown in the images above.

Step 13: Preparing Plaster

Place your mould on the board. Pour 8 cups of water into the bucket. Add a few squirts of watercolour. Pour 12 cups of plaster into the bucket, and stir using a spatula. Keep stirring until the mixture has an even consistency, and add more watercolour if desired.

Step 14: Pouring Plaster

Quickly pour the plaster into the mould, scraping the sides of the bucket down to use all the plaster. Tap the mould to the board to get rid of air bubbles. Put both the cores into the respective moulds, making sure they are centered by looking at it from the top. Use tape to secure the cores to the mould. Tap the mould to the table again.

Leave the plaster to dry for at least 24 hours.

Step 15: Opening the Mould

Use a box cutter knife to carefully cut through the tape between the pieces of the mould. You can also try pulling the pieces off. When the mould is off, use the knife to cut through the cores, and use your hands to pull them out of the moulds (try twisting/pulling it).

Step 16: Carving/Sanding

If the smaller cuboctahedron overfilled into the extra HIPS pieces, use a box cutter knife to slowly carve away the excess plaster. Cut away from your body with even strokes. Make sure this is done slowly and with precision. For minor imperfections, use sandpaper/a sanding board. One image above is before carving, the other two show the after.

Step 17: Finishing Touches

Use the box cutter knife to carve away any plaster stuck to the acrylic pieces, so that the shapes are more defined. Sand the insides of the cores and brush away any excess plaster. Place pens/pencils inside!