Making Molds with Oyumaru Instant Mold

oyumaru instant mold guideWelcome to today’s guide in which we are looking at a great product designed for quick and easy mold making. This is a Japanese product called Oyumaru, but is sometimes referred to as Instant Mold. It’s also low-cost, reusable, and has a huge amount of potential for use with gaming miniatures including allowing you to replace missing parts, and duplicate parts that you have sculpted and need more of.

Oyumaru is a non-stick silicone molding material, and one of it’s biggest selling points is that its completely reusable, so you can keep reusing the same Oyumaru to make completely different molds. This makes it perfect for people who need to make lots of molds, but only need a few casts of each piece. Here you can see the pack of Oyumaru we ordered, which was priced around £5 (approx $7.75).

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Inside the pack are six of these Oyumaru sticks. We chose blue Oyumaru but it is available in many vibrant colours, each Oyumaru stick is approx 60mm x15mm.

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The Oyumaru feels similar to a hard rubber, but can easily be cut with a craft knife depending on the size of the mold you want to create. For bigger molds you can combine these sticks together, although we’ve found that a little goes a long way.

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Now, what to make a mold of? …Well we do happen to have a Warhammer 40k Space Marine Dreadnought model which is sadly missing a one of his feet, so lets see if we can make a suitable replacement. Here you can see the part that we need to make another of:

Remember: We do not promote the use of Oyumaru to create copies of parts or complete models which would impact the products manufacturer financially or otherwise. Support manufacturers like Games Workshop by purchasing their kits, and then by all means use Oyumaru to personalise/convert or repair models as needed.

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Oyumaru is heat activated so all you need to do is drop it into some hot water for a few seconds and it will become very soft and easy sculpt with. Remember that if using very hot water, you should remove the Oyumaru with a craft knife or similar rather than your hands.

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Once softened by the heat of the water, the Oyumaru can easily be pressed around the part that you need to make a mold of. Remember to really push it into all the little gaps and force any air out so that it fits the original part as closely as possible.  When we have used this before we’ve found that Oyumaru is very good at picking up tiny details, which makes it perfect for use on wargaming projects.

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As the Oyumaru cools it will re-harden into its original dense rubber-like state, leaving you with a mold of the original piece.

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Once you have your mold you can simply fill it with Green Stuff (Kneadatite), Milliput, clay or any other modelling material. Since Oyumaru is non-stick you do not have to worry about the part or modelling material sticking to the mold, it will simply pop out.

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Here you can see the finished piece that we cast to fix our Dreadnought kit. After removing it from the mold we gave the part a quick trim with a hobby knife to remove any extra mold material from around the edges.

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And here is our repaired Space Marine Dreadnought kit. This Dreadnought is now ready to smite the enemies of the imperium in our games of Warhammer 40k!

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Once you’ve made and used a mold, you can simply drop the Oyumaru mold back into some hot water, let it soften, and then use it again to make a completely different mold. The fact that Oyumaru is so quick and easily reusable means that it now has a permanent place in our modeling tool box. We think Oyumaru is an excellent tool for wargaming projects, and would highly recommend it to anyone who enjoys the modeling and converting side of the hobby. Have you used Oyumaru? Do you have any further tips or tricks for using it? Let us know what you think in the comments below.

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