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How to Make a Mold for Epoxy Resin Casting

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Learn how to make a mold for epoxy resin casting – including a side by side comparison of different methods and all your questions answered! If you’re new to this, check out these basic resin techniques. This post contains affiliate links.


On my to do list, along with a zillion other things: make some resin coasters.

Why coasters, you ask? Well, they’re like a blank palette in a small, affordable size. Plus, they protect your furniture from annoying coffee rings if you ever remember to actually use it…

So I decided, instead of buying a coaster mold, why not spend more money experimenting with a few materials so that I can teach YOU how to make a mold for epoxy resin casting.

Table of Contents:

But then that begs the question: is it worth making your own molds? So stay tuned as I answer that and a zillion other questions regarding how to do it, what you can use to do it and more…

What’s the absolute best material for making a mold for resin?

The best way to make a mold for resin casting is using a two part silicone solution.

The reason that this is your best option is simple: it’s created exactly for this. You get a reusable mold, with a non-stick finish, that’ll last for many, many creations.

The main exception is if your project is too big. For very large projects that have geometric shapes, most people will build a framework from wood. However, that is way beyond the scope of this post. If you’re a beginner and you just want to make your own mold, I highly recommend that you go ahead and grab a box of two part silicone.

And here’s the catch. To cast your silicone mold, you need a mold!

Yeah, you heard that right.

Two part silicone is a liquid, which makes it work that much better. It captures every single detail and nuance of your original – including the texture. The mold that I made was from a wood slice. The final coaster has a matte finish.

To create a container for your silicone, you need something totally sealed so that it doesn’t seep out. Kind of like with resin…

So making molds for epoxy resin casting has so many similarities to actually casting the resin! The biggest difference is that when making the mold, you’re using a non-stick material, whereas resin does stick to things.

To cast your mold, you can use a plastic food container. If you find one in the shape of your resin needs (such as a simple round one) you can use this as a resin mold as well. When using resin, this is unlikely to stick. Something like mold release can help you over there.

You can also build your own DIY container from acetate sheets, which is what I did. Acetate does not stick to resin. So if you’re looking to make something with a simple rectangular shape, you can build your mold from acetate.

The biggest challenge will be truly sealing all your edges so that nothing seeps out – more on that below!

Which other materials can be used for Epoxy Resin Casting?

Two part silicone can be pricey. You may be better off just purchasing a mold for simple projects! More on that below, but meanwhile, I decided to see if I can cut costs by experimenting with other materials.

Can you use hot glue as a resin mold?

My first experiment was with something most crafters have handy: a hot glue gun. What a mess!

I took a coaster, covered it in petroleum jelly as a mold release. The hot glue just made a big mess. I used a non-stick surface (parchment paper) and let it dry thoroughly.

It took five large glue sticks (and those aren’t cheap either). And then it crumbled when I took it off.

There is the possibility that other brands or low heat sticks would work better. Mine were Gorilla brand.

If you want to give making resin molds from glue sticks a try, I recommend starting much smaller so that you don’t waste too much experimenting.

Can you make a mold using moldable plastic pellets?

Not long ago, I created a DIY seashell imprint pendant using heat-activated moldable pellets called InstaMorph.

This too failed, however, I do believe there may be further experimentation to do here, and I will update this space if I have success again in the future. If you do try it, please comment below and share your results.

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The reason it’s worth trying to make resin casting molds using moldable pellets is because they are reusable – making them very cost effective, especially for casual crafters and one-off projects!

To use InstaMorph, you pour them into hot water and allow them to turn clear. Lift them out with a stick (the water is too hot to touch.)

The pellets should be ready to handle. I placed my sea glass pieces on a piece of acetate and molded the Instamorph over it.

I waited until it turned white (a sign that it’s hardened). Then I tried removing the sea glass and ran into a number of problems.

Here are the problems and variations you can try if you want to give this a better shot:

  1. The heat melted the acetate, and on one of my sea glass pieces I couldn’t get it off at all. The fix: try parchment next time.
  2. It was still hard to get out, as it has very little flexibility. The fix: mold release. I also think that having it in a container as a ball and making a quick imprint by pressing in the object and removing it while still hot would help.
  3. And finally, when trying to make something with it, I used UV resin, not epoxy. And I couldn’t get the pellets off. It was totally stuck. I tried running it under hot water to soften it, and I saw that the resin seemed to have mixed with the plastic pellets.

In a nutshell, if you want to give this a go:

  • Try placing a ball of heated Instamorph in a glass container, pressing in your imprint and removing immediately.
  • Apply mold release before casting.
  • And only use it for Epoxy, not UV resin.

I do think this is worth another shot trying it this way, and I do hope to try it again, as it makes for a very cool one-off mold and is very very affordable.

Gave this a go? Comment below!

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Can you use acetate for resin molds?

Yes, you can use an acetate sheet as a resin mold, however there’s a way to do it. Since your resin catches any impression of any texture, acetate can give your resin projects a gorgeous, glossy finish.

You also need to be careful that any bends, ends of tape, or folds are at the corners or on the outside of the mold.

I used magic tape, which wasn’t strong enough and it leaked, but I still got a good idea of how acetate can work as a mold.

A few tips:

  • Make sure your sides are sturdy – no curving.
  • Measure sizing carefully – inconsistencies will show.
  • Use a durable tape that’ll seal it well.

I share details for how to do this in the step-by-step tutorial as it’s the same as making a casting dish for your silicone mold.

Can you use clay for resin molds?

One final option for making resin molds is clay. Clay comes in so many shapes and forms. And while not ideal, you can use uncured polymer clay to make resin molds. It’ll leave you with a rough, textured surface on your resin.

You’ll definitely want to use a mold release with polymer clay or your project will not release nicely.

Is it worth it to make your own molds for resin?

Now that all is said and done, we need to address the elephant in the room – is it even worth it to make your own molds for reason?

If the first reason you’re looking at how to make a mold for epoxy resin crafting is because you’re frustrated with the prohibitive cost of purchasing molds, you may be in for a shocker: it can be very expensive to make your own too!

Because of this I experimented with various materials. And I saw that the cheaper materials didn’t always work so well.

If trying an alternative method for making resin molds, always use a mold release agent. This can be corn starch, vegetable oil, etc. With silicone, I have never needed a mold release. But silicone is expensive.

Here are some reasons you still might want to make your own resin molds:

  • Custom sizes: If you can’t find the size you need for a mold, you can make it yourself!
  • Customized shapes: Again, if you’re looking for a very specific shape or to recreate a favorite item, you’ll want to make your own molds
  • Sentimental copies: Did Grandma have a favorite pendant that you’d love to recreate as ornaments for your family members? Making your own molds allows you to recreate sentimental items like that.
  • Hard to find: Harder to find molds and specialty molds can be prohibitively expensive even when you do find it. You may be better off making it yourself if you have a sample to cast handy.
  • More versatile to keep handy: If you are a hobby crafter and like to have your supplies handy when inspiration strikes, you likely won’t have every type of mold available. Having Mold Maker there for when you need it is much more versatile and space-efficient than stocking every type of mold you might want…
  • Crafting in bulk: Like many other things, the price for two part silicone drops significantly if you’re getting it in bulk. So if you plan to make a lot of resin molds, it may just be worth it…

Because of the extra steps, it’s probably only worthwhile if you plan to reuse it many times.

How to Make a Mold for Epoxy Resin Casting

Today, I’m sharing how to make a mold for epoxy resin casting using a two part silicone solution. This is, in my opinion, the only way that’s really worth trying.

I did share other methods briefly above, but for the step-by-step process, I’m sticking with the best way to do it.

In the process, you can make an acetate container, if you don’t have a food container. I share this as a separate process, that you CAN also use as a mold on its own.

Materials Needed to Make a Mold for Epoxy Resin Casting

How to make an acetate “container” for your silicone – or to use as a mold.

1. Cut a sheet of acetate to size. Take into account the height of your mold (plus a little extra). Cut a notch on each end the distance from the end that your container will be high, and as deep as your container will be high.

2. Fold up the flaps you just formed.

3. Fold up each side.

4. Tape them well so that the flap sits on the outside of the “container”.

Make sure no tape is on the inside or it’ll leave a seam. Make sure to seal it well so that no liquid can escape.

How to Make a Mold for Epoxy Resin Casting using two part silicone

1. If you’d like, you can cover the item you’re casting on the sides with a mold release.

2. Use hot glue to glue it well to the base of your container. make sure that no glue seeps out around it (or your silicone will cast that too). Follow the package instructions of the two-part silicone, regarding how much area to leave around the item you’re casting.

3. If you’re using a mold release, add it to the top of the item you’re casting. Make sure it’s free of debris or hot glue strings that might accidentally get cast too.

4. Follow package instructions to mix up your solution. Note: I do NOT recommend using silicone cups for this part like I did. I ruined them.

5. Stir it well according to package instructions, and until there are no streaks left.

6. Pour it over your prepared container (note: my container was much bigger than needed so I glued small pieces of sea glass in the corners to cast too).

If you didn’t prepare enough silicone, simply prepare more and pour on top. Allow it to cure according to package instructions.

7. When ready, remove the container to release your mold.

8. If you had some silicone seep under your item that you cast, you can carefully remove it by cutting it away with a pair of scissors or a knife.

9. Remove the item you cast. Your DIY resin mold is complete! Notice how every little nick on the wood slice coaster was cast (a benefit in this case.)

Now you can cast your new project! What a beauty! I hoped you enjoyed learning how to make a mold for epoxy resin casting! Got any tips to add? Tried something different and it worked? Please comment below to share your ideas!

How to Make a Mold for Epoxy Resin Casting

How to Make a Mold for Epoxy Resin Casting

Materials

Instructions

How to make an acetate "container" for your silicone - or to use as a mold.

    1. Cut a sheet of acetate to size. Take into account the height of your mold (plus a little extra). Cut a notch on each end the distance from the end that your container will be high, and as deep as your container will be high.

    2. Fold up the flaps you just formed.

    3. Fold up each side.

    4. Tape them well so that the flap sits on the outside of the "container".

    Make sure no tape is on the inside or it'll leave a seam. Make sure to seal it well so that no liquid can escape.

How to Make a Mold for Epoxy Resin Casting using two part silicone

    1. If you'd like, you can cover the item you're casting on the sides with a mold release.

    2. Use hot glue to glue it well to the base of your container. make sure that no glue seeps out around it (or your silicone will cast that too). Follow the package instructions of the two-part silicone, regarding how much area to leave around the item you're casting.

    3. If you're using a mold release, add it to the top of the item you're casting. Make sure it's free of debris or hot glue strings that might accidentally get cast too.

    4. Follow package instructions to mix up your solution. Note: I do NOT recommend using silicone cups for this part like I did. I ruined them.

    5. Stir it well according to package instructions, and until there are no streaks left.

    6. Pour it over your prepared container (note: my container was much bigger than needed so I glued small pieces of sea glass in the corners to cast too).

    If you didn't prepare enough silicone, simply prepare more and pour on top. Allow it to cure according to package instructions.

    7. When ready, remove the container to release your mold.

    8. If you had some silicone seep under your item that you cast, you can carefully remove it by cutting it away with a pair of scissors or a knife.

    9. Remove the item you cast. Your DIY resin mold is complete! Notice how every little nick on the wood slice coaster was cast (a benefit in this case.)

Did you make this project?

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