Casting With Molds Made With Papercraft Models

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Introduction: Casting With Molds Made With Papercraft Models

You dont't have to use paper. Cardboard, plastic sheets, even metal would work.

Any cast starts with a mold. You need something to pour your material into, be it concrete, plaster, resin, wax, whatever. You can user everyday objects like bowls, packaging or make molds from existing objects.

But what if you want cast something completely different? Something you can't make casts of?

Paper to the rescue. Everyone has some lying around, has scissors and glue. And paper can take pretty much any form you want.
It does have it's limitations though. It's not waterproof and will lose it's strength when getting wet. So before you can use it as a mold, you'll have to make it waterproof. I'll just use spraypaint. Also it's strength is limited. So making huge casts doesn't work. The "Venus de Milo" is 36cm (14 inch) high - and it worked out just fine.

Paper is great to work with, it's easy to cut, fold and glue. But if you want to make more than one cast of your mold you might want to try sheets of plastic. While it is a lot harder to work with it is reusable. You can make many casts with the same mold over and over.

Here are two different routes I took

Step 1: The "gothic" Vase

This is the last one I made and it's the one I documented best.

It's a cast made from David Huffmans "Hexagonal column with cusps". I took the blueprint from the following paper by Erik and Martin Demain and Duks Koschitz.

There is a tutorial on youtube on how to fold it:

Step 2: Printing and Folding David Huffmans Vase

The paper I mentioned before includes the template seen above. You'll need to print it out the size you want your vase to be. I used A4 the resulting vase will be 13 cm (5 inches) high. If you want a bigger one adjust your print size.

I knew that I wanted to try out many different materials, so I used a sheet of translucent plastic I got from my local craft department. I then scored the lines using a tool to pinch holes. Just make sure you don't punch through the plastic. If you do, you can just cover the hole with scotch-tape.

Now comes the tricky part, folding it. If you have trouble here, take a look at the video in the previous step.

Step 3: Making It Watertight

3D-modelers know the term watertight. On the screen it's just a virtual term. This is real life. It actually has to be watertight or else whatever you will pour into the mold will splatter all over your workplace.

Start with the back. tape the two sides together.

Then trace the resulting top and bottom and cut out the parts. Make sure you leave a hole in the top. We need an opening to pour the casting material into.

I used a glue-gun to seal the top and tape for the bottom.

The cardboard I used worked surprisingly well. It does get soaked but it strong enough to hold it's shape.

Step 4: Prepare the Casting Material

The first material I used was Acrystal (in german). A water based mineral resin. I like it because it doesn't smell. You can actually use it indoor. It cures reasonably fast making it ideal for roto-casting.
After it has cured it is not totally waterproof. More like terracotta. It holds liquids and won't dissolve, but over time water gets soaked up. I just pour in a layer of paint at the end. that seals it off.

I successfully made casts with plaster and resin-plaster.

Concrete should work if you build a second inner form. Rotation-casting doesn't work with concrete. After all, that what the concrete mixers do to prevent the concrete from getting hard. Maybe there is a form of concrete that can be roto-casted. Does anyone know?

The images above show what I've done. I wanted the cast to have a color, so I mixed the mineral part of the resin with petrol colored pigments. The pigments you'd use to make your own acrylic paint for example.

Shake to get an even distribution of the mineral and pigments.

Add the liquid part of the resin and stir until all is well mixed.

Pour into the mold.

Step 5: Rotation Casting

Now roll and rock ;) your form. the resind has to flow into all parts of your mold. Just make sure it doesn't drip out of the hole on the top. If you want to make sure that it doesn't cover it up with tape.

It will take a few minutes. Don't be hasty with your movements, the resin will become less and less fluid and will stop to move after about 5-10 minutes.

Yeah! Almost done...

The wall thickness of your vase will be too thin by now. So you will have to repeat this step a few times to build up a stable wall. I used a second colored layer. Then a layer where I mixed in sand as a filler. and a fourth plain layer.

Step 6: Cleaning Up

Not your workspace, the vase. ;) Removing the cast from the mold is easy. Only the top and bottom made of cardboard stick to it. The can be removed with water.

I left mine out overnight to cure and dry.

The next day I applied the inner layer of paint to seal it.

After the paint dried I used rasps and files to trim the hole at the top.

Step 7: The First Vase - Done

This was part one. It actually took me longer to take the pictures and write this up, than to make the vase. So while it might seem a little intimidating at first, believe me - it's not that hard. And you'll be amazed how a flat sheet can turn into such a complex vase.

On to the next one - Venus:

Step 8: Start - Venus De Milo

Some of you have seen my first instructables. It explains how you can turn a virtual 3D-model into a real paper model. The deer is the example it took back then, check it out.

I used a model of the Venus de Milo this time using the same technique as with the deer. So again, if you want to see how the cast ist made, look at how I made the deer. The only difference is, that I spray-painted the paper model to make the paper watertight.

Then I used the same resin as with the "gothic" vase in the steps before.

Step 9: Birth of a Venus

I didn't get the model really watertight. So I made quite a mess with drops of resin coming out all over the model. Need to be more careful the next time.

After it cured I started to peel back the paper on her back. It came off surprisingly easy. The paper mold gets destroyed though. I don't think there is a way to save it.

A great feeling to see it emerge from the mold.

Step 10: Failure

Whenever you experiment or you are trying something new - be prepared to fail.

Not all models make good molds. Some are just too delicate as the one above.

And yes, sometimes the color is just too tacky. ;)

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    63 Discussions

    Thank you for your article. I am working on a big project: I am trying to make a big resin frame and cast coins in it. My project has failed so many time and I am discouraged now. I haven't been able to make a mold of my box. Can I just use the big cardboard box and pour my resin in it? Do I have to seal the cardboard and use a mold releaser?

    I have been trying to make a mold (using silicone+cornstarch) of a big box. I haven't been able to get a nice mold of it since it is pretty big and difficult to shape the entire silicone mold before it starts setting.

    Please help me!!!!

    1 more answer

    I coated mine so that they wouldn't soak up the moisture and get weak. Paper and cardboard loose all their strength when they get wet. The bigger your mold gets the more you might have to stabilize it. Maybe a wooden frame might help.

    This is great and I've done something similar recently with a low-poly Iron Man Helmet (my own Instructable to follow...)

    I was just wondering how you got the paper/card to come off? I used 300gsm card and polyeurethane resin, but once the resin has cured, the card isn't able to come away from it. It tears slightly at the edge, and the rest just stays in place, almost as one with the resin underneath.

    Any advice?

    Great work! Really inspiring! So much so that I want to do a life-sized version of Venus de Milo. Do you think this is doable? I know you said you can enlarge your settings for a larger model but one that is life-sized...how would that work?

    Thank you, in advance...

    6 replies

    If you want it "just in paper" shouldn't be a problem. Use card stock. Haven't tried it that big, but I would assume that it should work.
    Casting it, I doubt it. You would need a lot of material with a lot of weight. I doubt that a life-sized cast with cardboard or the plastic sheets would work. You'd have to use metal sheets I guess.

    I used Krummrey's other ible to design and build this, and really if worst comes to worst you can use PVC pipe to build a skeleton to support the weight. This one didn't really need it since it's still small (only 3 feet at the top of antlers) but I did have to use it to keep the legs spaced correctly.

    Also, Krummrey you never stop stunning me lol, it seems like every 'ible you do just gets cooler and cooler.

    20140511_221416.jpg20140511_221427.jpg

    puedes enviarme el PDO - PDF?

    send me to : casa.uu@gmail.com

    That is amazing!!! And it looks HUGE. I'm stunned by how many people have built the deer and moose. And even more amazed by those who took it further and have made their own designs.

    Thanks for the compliments. I'm standing on the shoulders of giants here. Picking up what others have done before.

    awesome! :D THANKS

    Hi there!

    I've just got a pro memebership just to be able to make the Venus of Milo, but your PDF doesn´t include the blueprint of it. Can you send it to me please?

    mi email bratt20elf@gmail.com

    1 reply

    Sorry, I don'r have the PDF for the venus anymore.
    But I have an instructable that shows you how you can make it yourself:
    https://www.instructables.com/id/Create-faceted-paper-objects/

    Sorry, I misplaced the pepakura files. I didn't know that I would make an instructable out of it. Sorry.

    Hi there!

    I've just got a pro memebership just to be able to make the Venus of Milo, but your PDF doesn´t include the blueprint of it. Can you send it to me please? aleida.reveles@gmail.com

    Best regards

    Really neat instructable! Thanks!

    Thanks, I'd love to try them out in concrete... Let's see what the judges think about that :D