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Making a soap mold from a 3d model?


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Posted · Making a soap mold from a 3d model?

Hi there,

I am trying to make soap molds from 3d models, what i am thinking is having a 3d model and then slicing it in half making it flat on one side and then making it hollow to fill in with soap, how would i do this?


Model example: https://www.turbosquid.com/3d-models/sample-english-bulldog-real-time-3d-model-1155164

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    Posted · Making a soap mold from a 3d model?

    OkeeDokee. Mold making can be tricky in some cases. I wanted to make sure that was the case before I went nuts replying.


    I really suggest you do real research (Youtube is great in this case) to see some of those issues that I see no matter how you turn it. This thing has tons of what is called 'undercuts' that would require multi-part mold. And then techniques such as printing a positive and then casting a soft material such as soft silicon in/around it to make the final negative to cast your soap.


    And, then, depending on aesthetics, there are things that you can do to ease that pain.


    And, then, what modeling program would you want to work in. In this case I would avoid any engineering Programs as this model is organic in nature. Volumetrics would be ideal if you are just slicing up an already made model such as the bulldog. Volumetrics are just blindingly fast. Blender actually gives you both Mesh modeling with a lot of tools and volumetrics too. In a way, the best of both worlds.

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    Posted · Making a soap mold from a 3d model?

    I have no experience with soap models, but with moulding and casting in general with silicones, yes.


    First, I would suggest you start with a simpler model, a dolphin or shark, that can be made in a two-part mould. And then, as kmanstudios said, go to Youtube and search for: silicone mould making and casting


    This gives a wealth of information, with hundreds of very good tutorials, and product info.


    What I often do is: first print the model in PLA. Then in plasticine (a no-sulphur variant) I model a box closely around the part. And then I pour liquid silicone into the box. After curing, I remove the plasticine, and very carefully cut the silicone on appropriate places. These seam-lines are important: they should be in a place that does not deform the model, and they should allow you to remove the model from the silicone mould. Also, the seams should make it possible to assemble and align the mould correctly later on.

    Another option is to use paste-on silicone. Paste that onto the model and let cure. Then paste shell-material onto it: this is a paste that hardens into a very hard plastic, like polyester. Some people use gypsum too. Make the shell so that it can be removed, thus in multiple parts. Include alignment features in the shell, so it fits back together in the correct position later on.


    And provide channels in which you can pour the soap, and through which entrapped air can escape.


    There are lots and lots of things to consider and keep in mind. Making a good mould takes a lot of planning and studying, even for fairly simple models. Hence the importance of the Youtube tutorials: even if you spend a whole day studying them, you will soon win that time back.


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    Posted · Making a soap mold from a 3d model?

    Mostly you need some kind of cad software to break up a model into multiple portions.  But one cheap trick you can do with cura is to go into preferences and uncheck "automatically drop models to the build plate".  Then click your model to select it and go to "move" mode if you aren't already and set the Z position to a negative value.  This will "sink" your part below the build plate and it won't print anything below the build plate.  Then you can duplicate your part, flip it 180 degrees and repeat.  If you click the "scale" tool instead of "move" you can see the total Z height of the part before you do this and make sure your negative Z values add up to the total Z height such that the parts are split at the exact same plane.


    But I've never done this because it's too much of a hack.  Much better to split the part up in CAD as it gives you more options.

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    Posted · Making a soap mold from a 3d model?

    There are also openscad mold generators floating around the internet. You can use those to specify how many parts you want the mold to be and they will also generate connectors. 

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