Selecting a model for your mold – resin mold making tips

tips for selecting a model for your next mold

When it comes to making a resin mold, regardless of what kind, style, etc., there is one basic place to start:

You need a model.

Let me say it again.

You need a model.

I get numerous email requests for help with a custom mold only to find out the resin crafter doesn’t have a template.  In order for you to mold something, you must have a model.  You cannot carve out silicone or create a shape in the silicone without a template.

So what are my suggestions for selecting a model for your mold?

Almost anything can serve as a model for a mold.  This is especially true if we are talking about a pourable or semi-solid molding material.  Here are a few examples of some materials that are suitable for models:  wax, metal, clay, bone, plastic, wood, plaster, stone, and other resin castings.  A note on your model choice, be sure you are not violating any copyright laws.  While it’s one thing to mold and recast someone else’s design for your own personal use for a few pieces, it’s another thing to recast something and sell it to others.  If you are unsure if your model is legal for you to use, get some advice from an attorney.

So what happens if you have an idea for a mold, but don’t have a model?

You are going to have to create your own.  Here are several examples that can help you create a model:

1.  Let’s say you want to make a paperweight that measures two inches square by 1 inch tall.  See if you can find a woodworker in your area that will cut, sand and polish a wood piece that can serve as the template for your mold.

2.  Have a more complicated design?  Find someone experienced in CAD/CAM work that can create a wax prototype for you.  Wax models are great templates for silicone molds.

3.  Good with a computer?  There are several online companies that will allow you to upload a design via a computer file that can be printed as a three-dimensional object.  Do it in something like plastic to easily allow it to become the model for your next mold.

So now you have a model.  What do you do to make sure you are successful at making a mold?

1.   Build or secure an appropriate mold container for your piece.  Empty plastic food containers are a great choice for a mold box.  They are inexpensive and generally very flexible.  If you are going to build a mold box, make sure all sides are leak proof.

2.  If your model is porous (wood for example), make sure you seal it before using it with a mold-making material.  Otherwise, the mold material may adhere to the model via small holes and make it impossible to demold later.

3.  The last step before pouring in the mold material is to cover it with a light coat of a resin mold release agent.

Uh, this pouring silicone looks really hard.  Is there something else I can try?

Yes!  Two-part silicone mold putty is easy to use and can also make great molds.  This article shows how to use silicone putty to make a mold of a Lego.

Like this post? You may be interested in  How to seal papers or findings for including in resin

What other questions do you have about selecting a model for your mold?

Unpublished Blog Posts of Resin Obsession, LLC © 2020 Resin Obsession, LLC

13 thoughts on “Selecting a model for your mold – resin mold making tips

  1. One of the reasons I want a 3D printer is so that I can make mold models entirely my own. I’m not all that good at sculpture but I can do stuff with computer graphics.

  2. is composimold safe if i will use polystyrene materials (miniature car parts, accessories, assorted model kit parts) ,im having doubts maybe it will melt.

    1. Hi Gen, it depends on what you are trying to mold. I’m afraid there isn’t a ‘one size fits all’ answer.

  3. Hi. Thanks for all the advices. I have three questions:
    – in order to have a glossy finished resin product we need to have a glossy mold so Which material of model is best to achieve a glossy mold?
    – After made my mold, I tried casting it with resin but it has a lot of bubbles rough bumpy surface, like a sandy feeling when you touch it. What did I do wrong do you have any idea?
    – Which material is best for mold frame? The design I try to mold is big and there is no plastic container can fit it!


      1. Thank you so much for replying to my msg. I didn’t expect it happened so quick.
        I just read those points in the link, will give it a try but just another question to reassure myself. So the type and mould I used won’t create the bubble in resin? I did a test, if I sprayed mould release agent it would give a bubble rough surface, if I didn’t it would come out fine but not shiny.
        Would cardboard paper or construction paper be a good choice for a mould frame?
        Do you have any mould making classes? I would love to join. Thanks

        1. Hi Crystal, the mold shouldn’t create any bubbles, unless it is one made from mold putty. Sometimes those can trap air bubbles, but you can bake it in a warm oven for an hour or two to get the bubbles out. If using mold release causes a frosted finish on your resin, then try using less. Unfortunately, cardboard and paper aren’t strong enough to serve as a mold box. I don’t offer any mold-making classes at this time.

  4. Hi Katherine,
    Sorry for being annoying but I tried for an hour looking for Tyvek and still don’t have any clue what is that. As I mentioned I need something to build a mould box/frame when doing silicone mold. Plexiglass a bit hard, can’t do curve or round. 😭

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