(18+) Poor man’s Modeling Part 3: Duplicate part with two-part Oyumaru mold & Plaster

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This is Part 3 of Poor man’s Modeling! I have some free time this week so I decide to pickup what I had left from last year. XD Here I’ll show you how to use Oyumaru (plastic clay) to duplicate a figure. Oyumaru is a reusable putty, which is softened by heat. Once shaped it cools and hardens in just minutes into a hard, slightly rubbery, plastic. It does not stick to Art Clay, PMC, polymer clay, Green Stuff, Kneadatite, Epoxy Putty, Stick Putty and other common sculpting putties.

I have been using Oyumaru for molding for a very long time. Long before they were called Oyumaru. It is very easy to use but hard to master. You will always get some flaws here and there. It always take me 2-3 tries until I get an acceptabe mold. But still I have to fix the cast with sand paper and putty.

These are the items that I’ll be using for making the 2-part mold today. 1) Oyumaru 2) Heat gun/hair dryer 3) Baking paper/tracing paper 4) Metal tray

This is Oyumaru! They are sold in different packages. You can buy them in a pack of 2/3/5/6/7/12/24 pieces. The one I have here is a 24 pieces pack. They’re cheap. This 24 pieces pack only cost around $14 (with free shipping) on Amazon. Or you can get the 6 pieces pack for around $7 (with free shipping) on Amazon.

Here is the instruction. Place the Oyumaru in hot water (over 80°C/176°F) for around 3 minutes. Once soft, you can shape it as you like and it wil harden when it cools down. But I’m not going to use hot water, I’ll use heat gun instead.

I had a very bad experience with heating Oyumaru with hot water. No, I didn’t burn myself. I just didn’t dry a small block of Oymaru (1-2 pieces) before shaping it. A lot of water drops were trapped inside the Oyumaru but I didn’t think it was a serious problem. Then I mixed that contaminated small block into another block of Oyumaru (~4 pieces).

Now the contaminated small block (1-2 pieces) became a big contaminated block (~6 pieces). When I tried to make a mold of a figure, the problem appeared. Because water couldn’t be compressed, a lot of tiny bumps appeared on the surface of the mold!!!

Once the water was trapped inside, there was no way for me to remove the water from it unless I chop it into very tiny pieces. I tried to dry it with heat gun (stupid me), but it only caused the water became steam, expended and bubbling inside the Oyumaru. At the end I had to throw away that big block of Oyuman. =(

  • Preparing the figure

Here is what I’m going to duplicate today. My beloved Kokuten Tae (18+)!

I’m going to duplicate the body only. To make the job easier, let’s take the head off first. I tried to remove the left arm too but it was glued tight so I gave up. Make sure the figure is clean. If you clean the figure with water, make sure you dry it thoroughly. You don’t want any water trapped between you figure and the mold.

  • Making the Front Mold with new Oyumaru

It requires multiple molds to duplicate the whole body. It is doable but not that easy to do a big multiple molds with Oyumaru. So I decided to do the torso only with 2-part mold. For the front part mold, 4 pieces is enough.

I’m NOT going to heat up the Oyumaru with hot water. Instead I’m using Heat Gun. If you don’t have a Heat Gun, you can use Hair Dryer but it will take a bit longer to warm up the Oyumaru. It is not necessary to use metal tray. But it helps to warm up the under side of the Oyumaru a lot. Oyumaru is very sticky when hot. The baking paper/tracing paper is to prevent it to stick to the metal tray.

Be very careful when using a Heat Gun. The air coming out from a Heat Gun is super hot. The lowest setting of my cheapo Heat Gun is around 375°C. A lot of Heat Gun can reach 1000°C easily. It only requires 80°C to warm up the Oyumaru. With 375°C, you can warm up the Oyumaru within a minute.

You can stop when you see the Oyumaru is melting like this. Actually it is overkill already. Let it cool down a bit for a minute or so until it is warm enough to touch.

  • Applying the Oyumaru to the Figure

Now let’s cover the Oyumaru to the front of the figure. Remember this is a 2-part mold. All you need to do is cover the front part.

Just like applying screen protector on your cellphone. Air pocket is a big no no. So try to apply the Oyumaru from top to bottom or from bottom to top slowly. To get the most details out the figure, press the Oyumaru slightly but try not to make it too thin. The mold might not hold its shape during casting if it is too thin.

  • Making the Back Mold with old Oyumaru

Did I say Oyumaru is reusable? Here I’ll show you how to reuse the old one for the back part of the 2-part mold.

First you need to make sure the old Oyumaru is clean. You don’t want to contaminate it with the old casting material or dirty. You can wash it with water and clean it with an old toothbrush. Remember to dry it thoroughly.

You can heat them up in big pieces just like this.

But if your old Oyumaru has a lot of air bubbles like this one. It is a good idea to cut it into tiny pieces before heating it.

I find that you can eliminate a lot of air bubbles if you cut them into tiny pieces before heating it.

When they’re all heated up, you can mold them together into a big piece. But if you apply this piece onto the figure, you will not have a good result. To make a nice mold, a smooth surface is a must. The surface of this piece is too rough.

To make a smooth surface, all you need to do is stretching it and fold it a couple times.

Some air bubbles will be trapped between layers during the folding process. But it is ok as long as the bubbles are in the middle, not on the surface.

After it cools down, you can cut it into the shape that you need before heating it again and apply it to the figure.

Oh by the way, the surface of Oyumaru will be come glossy when it is heated up.

If you see some air bubbles on the surface, you just need to pop them with some sharp objects.

Once you’re happy with the surface, you can apply the Oyumaru to the back just like how you did for the fornt.

  • Examine the Mold

After it cools down, you can take it apart. Now the 2-part mold is done!!! Easy right? =D

Now let’s check it out. Here is the back mold. It looks alright.

But the front is another story. It has way tooooo many air pockets and cracks. They will show up in the cast. Remembered what I said in the very beginning? Oyumaru is very easy to use but hard to master. You will always get some flaws here and there. It always take me 2-3 tries until I get an acceptabe mold.

I’ll redo it all over again. I’m not going to junk this mold just yet. I’ll cast this mold show you guys how those flaws ruin the cast.

Here is my second attemp. There is still some flaws but it is a lot better than the previous one.

  • Preparing for Casting

As usual, I’m using Plaster of Paris for my poor man’s casting material. But before that, let’s prepare the mold for casting first.

Here is the 2-part mold. If you pour the plaster into the mold just like this, the plaster will come out from the holes and gaps.

To cover those holes and gaps, I’ll use oil-based modeling clay. To learn more about oil-based modeling clay, please read Part 2: Duplicate part with one-part Clay mold & Plaster. You can use other type of clay or even Play-Doh will work too.

First I made the clay into a cup which is big enough to fit the 2-part mold in.

Then squeeze it. Don’t squeeze it too hard. You don’t want to deform the mold. LOL, it looks like an Ebi Tempura!! XD

  • Bonus Round

Since I have some Oyumaru left from the “After it cools down, you can cut it into the shape…” process. I’m going to use the leftover to duplicate the pu$$y of Imako-san (18+).

I’ll use this pu$$y for Makaizou (18+) with another figure later.

Here is the 1-piece mold of the pu$$y. I cover it with clay too.

  • Casting

I bought this Plaster of Paris many years ago. It was cheap, less then CAD$6 for 2kg. You can get it for around US$3 for 4lb, US$8.50 for 25lbs on Amazon.

Don’t forget to read the mixing instructions! “2 parts Plaster of Paris to 1 part cold water”

If you want to make the plaster stronger, you can add some white glue into the mixture.

Ebi Tempura 2-part mold of Kokuten Tae (top); Flawed mold (middle); Imako-san’s pu$$y (bottom)

For the 1-part mold, to prevent air bubble forming on the surface of the cast, instead of pouring in the plaster all at once, you can coat a thin layer of plaster on the surface with a small paint brush first.

As for the 2-part mold, not much you can do about it. All you can do is keep pounding it and hopfully the air bubbles will come out by themselves while pouring in the plaster. Of course you can always use a vacuum chamber or pressure chamber to get rid of air bubbles. But this is a guild for poor man. Those things are not for poor man. =P

  • Final Result

Accounting to the Plaster of Paris’ instruction, it will set in 20-30 minutes. But I waited 2 hours just in case. Let’s check out the flawed mold first. You can clearly see the horrible air pockets and cracks show up in the cast.

Here is Imako-san’s pus$$y. It looks really good! Casting small pieces with Oyumaru is very easy. I believe even beginner can do it right in a few time.

Now let’s check out the Ebi Tempura 2-part mold of Kokuten Tae. There are some flaws here and there too. You can see a big air pocket on the stomach, a small line on the left thigh, and both nipples are missing. With sand paper and a little putty, those things can be fixed easily.

Because it is a 2-part mold, casting material bleeding from the gap is expected. Those are easy fix with sand paper so don’t bother with it.

You know what? It think it looks like an art piece! It looks like those anncient Greek sculptures that missed the arms, legs, and head! Maybe I’ll make a stand for it and display it like an anncient Greek sculpture. =P

  • Final

Unlike the Gelatine mold and the Clay mold, Oyumaru is designed for making mold. It is reusable, very easy to use, and picks up detail surprisingly well. But it is not mean for mass production. Some details on the mold will lose after 3-4 casting. If you think you can mass production bootleg figures with Oyumaru, you better think it twice. XD

If you have any question, you can ask me on the Nekomagic Facebook page.