Casting Plaster: the Legendary Pencil Holder Tutorial

Very simple. Follow along. Make dat thing in the picture (๑•̀ㅂ•́)و✧

Please be sure to click on more images for every single step as it will truly help you understand exactly what you need to do each step ヽ( ^∀^)ﾉ

*and for ya'll who is trying to find "inspiration" for your casting plaster unit, feel free to use this instructable as your template. I got 8 8 8 8 on the unit anyways

》it is old saying that a picture worth like lot of words. 《

1. Pencil = pen = marker = anything you can use to draw on high impact polystyrene

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note: when you get the high impact polystyrene look for a thickness around 0.5 mm. It will make it a lot easier to cut with scissors. TRUST MEEE

Here we demonstrate how to make the mould of the pencil case

》Draw a 7cm square with compass《

(Compass, ruler, protractor, marker)

1. Draw a 7cm line on the high impact polystyrene, mark the center of the line (3.5cm)

2. Set the compass to 3.5cm wide like shown above

3. Use this length as the radius and draw a circle using the center of the line as the center point

4. Use the points where the the first circle intercept with the line as the center points, draw 2 more circles

5. Drop a perpendicular line at the first circle's center, if you don't know how to do this please go see a psychiatrist immediately

6. Use the points where the the perpendicular line intercept with the first circle as the center points, draw 2 more circles

7. Connect the petals where the 4 circles cross

8. A perfect square

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note: obviously you could just use the protractor and measure 90 degrees or use set-squares φ(≧ω≦*)♪

》Cut out the square from the previous step《

(Scissor)

1. Get the scissor

2. Align the blade with the sides of the square

3. Cut out the square

》Draw a isosceles triangle《

(Compass, ruler, protractor, marker)

1. Draw a 7cm line on the high impact polystyrene, mark the center of the line (3.5cm)

2. Drop a 9cm perpendicular line at the first line's center, if you don't know how to do this please also go see a psychiatrist immediately

3. Connect the top of the 9cm with the two ends of the 7cm line

4. A perfect triangle

》Cut the triangle from the previous step《

(Scissor)

1. Get the scissor

2. Align the blade with the sides of the triangle

3. Cut out the triangle

》We need 7 more of the triangle...《

(Compass, ruler, protractor, marker, scissor, tape, triangle)

Method 1:

1. Repeat step 4 and 5 seven more times until you have 8 triangles in total

Method 2:

1. Stick the triangle we cut out on to the polystyrene using tape

2. Use that triangle as the guide and cut the polystyrene under

3. A exact same triangle!

3. Repeat this until you have 8 triangles in total

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note: the second method is way simpler! ( *・ω・)✄

》Taping everything together into a geometric net《

(Tape, scissor)

1. Place the bigger square and triangle like shown above, make sure you are taping the side that does not reflect light because we will be using that side as the inside of the mould. Taping it would leave tape marks on the final product

2. Tape the edges together and make sure there are no gap between the tapes

3. Repeat 4 times for all for sides

4. Place another triangle next to the taped triangles like shown above

5. Tape them together

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》Taping everything together into a 3D Mould《

(Tape, scissor)

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1. Setup the 2 arm of the net as shown

2. Tape the edges together and leave no gaps

3. Repeat until it looks like it in the pictures

4. Done!

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note: make sure it is absolutely sealed with tape!

Here we demonstrate how to make the cuboid core of the pencil case

》Draw a 5.5cm square with protractor《

(Ruler, protractor, marker)

1. Draw a 5.5cm line on the high impact polystyrene

2. Use the protractor to measure an 90 degree angle on one end of the line, mark the direction

3. Align the ruler with the mark and draw another 5.5 cm line

4. Repeat this for the other end

5. Collect the end of the two new lines

6. Boom. A square!

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note: i am sure there is not point explaining how to use a protractor to draw an 90 degree angles. ㄟ( ▔, ▔ )ㄏ

but please bear with me, this is for educational purposes

》Cut out the 5.5cm square《

(Scissor)

1. Get the scissor

2. Align the blade with the sides of the square

3. Cut out the square

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》We need one more...《

(Scissor, tape)

1. Stick the square we just cut out on to the polystyrene using tape

2. Use that square as the guide and cut the polystyrene under

3. Another exact same square!

》Drawing the 5.5cm✖️7cm rectangle《

(Ruler, protractor, marker)

1. Draw a 7cm line

2. Draw 2 perpendicular 5.5cm line

3. Connect them

4. You got your rectangle

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note: at this point, if you still don't understand how to draw a rectangle, please call an ambulance immediately due to possibility of severe brain damage. ✧(≖ ◡ ≖✿)

》Cut the rectangle from the previous step《

(Scissor, tape)

1. Get the scissor

2. Align the blade with the sides of the rectangle

3. Cut out the rectangle

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》We need 3 more...《

(Scissor, tape)

1. Stick the rectangle we cut out on to the polystyrene using tape

2. Use that rectangle as the guide and cut the polystyrene under

3. A exact same rectangle!

4. Repeat until you have 4 rectangles in total

》Taping everything together into a geometric net《

(Tape, scissor)

1. Place the smaller square and the rectangle like shown above

2. Tape the edges together and make sure there are no gap between the tapes

3. Repeat 4 times for all for sides

4. Place another triangle next to the taped triangles like shown above

5. Tape them together

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》Taping everything together into a 3D Mould《

(Tape, scissor)

1. Setup 2 arms of the net as shown

2. Tape the edges together and leave no gaps

3. Repeat until it looks like the 3D shape in the pictures

4. Tape the final pieces of square on the top and you will end up with a cuboid as above

4. Done! (make sure it is fully sealed!)

Here we demonstrate how to make the final product (cast with the mould and core, touch up, etc)

》Casting with plaster《

(Plaster, bucket, stirring 'stick', cups, water)

1. REMEMBER! The ratio of water to plaster is 2:3

2. Add two water to the bucket using whatever container you think will be enough for the mould

4. Add three plaster using a same sized container

5. Stir until the plaster and water is complexly mixed up and there are no solid blocks in the bucket

6. Add the mixture into the mould

7. Shake it up and down a bit to allow the air bubbles out in order to get a smoother texture

8. Place the core in the center and push it down into the mixture, leaving roughly 1cm of core above

9. Hold the core until the mixture solidify and holds itself. Also the mould would certainly go outwards a bit under pressure, so make sure you push the sides and maintain a perfect square shape.

10. After it solidify take it to a safe place for it to fully dry up and clean up the area

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note: doing this outside of your house is highly recommended as it could make a lot of mess ʅ(‾◡◝)ʃ

》General tips for taking out the mould《

(Utility knife)

1. Wait 24 hours for the plaster to be become pretty much solid and stay in shape even if you take the mould out.

2. Be very careful with it as at this stage the plaster is still soft and can still be easily damage, but this is also the reason why we take it out now as we can still change it easily.

3. If there are pieces of plaster you don't want , DO NOT TRY TO WASH IT as the thing would start dissolving. Gently wipe them away using your thumb or tissue.

4. It depends on what kind of casting plaster you used but they mostly all kinds become fully sturdy after a week or so, and by than it would be real hard to reshape it.

5. When you cut the tape, do not cut like the first picture above as it is very hard to control and would easily leave marks on the actual thing.

7. Cut open a small gap first, and then cut side ways with the blade parallel to the side you are cutting.

6. Repeat until you can peel the mould off. congratulations!

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》Taking out the core《

(Utility knife, scissor)

1. First remove the top of the core

2. Bend the side inwards like shown

3. Use the scissor to cut each side of the core in half or more, completely destroy it

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note: I apologies I could not use the mould and core we made as the example. But you'll get the point (oﾟωﾟo)

》Flattening out the top, removing unwanted pieces 《

(Utility knife)

1. It is likely that the top of the pencil cage will not be completely flat. Use the knife to cut out wanted edges and etc like shown above.

2. If there are unwanted edge pieces like in picture 3, don't use the knife to trim them as you could end up removing the entire edge. Simply push with your thumb and they will come off.

3. Feel free to sand it but you could end up with ugly and rough texture, thus sanding is not recommended.

Share the final product with your friends and families (POSSIBLY NONE) or whatever.