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"Using Oyumaru/Blue Stuff For Making Your Own Moulds" Topic

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Asteroid X07 Jul 2020 9:12 a.m. PST

There are a number of videos available on using Oyumaru to cast your own pieces, but what is the experience on here?

Specifically, what compound do you find the easiest to cast with? Green Stuff? Milliput? Apoxy Sculpt? Etc?

I have read about a 50/50 mix of Green Stuff and Milliput, but have not tried that yet.

Also, how are you making the moulds? Just pressing the soft pieces together by hand or using a Lego frame or clamps or ?

John Leahy Sponsoring Member of TMP07 Jul 2020 10:34 a.m. PST

I recently did this. I did the molds for shields by hand as 1 piece molds. I just used Green stuff. I did buy some Milliput to mix with it. It is dirt simple to do. Results are pretty good too. If I did larger 2 piece molds I might use lego. I have a lot of experience making molds for resin and metal figs via homecasting. Started doing it about 40 years ago.



Thresher0107 Jul 2020 10:58 a.m. PST

Lego frames should help minimize warping.

In the past I've used latex, and just made a backing from plaster for it. Worked pretty well too.

Waco Joe07 Jul 2020 7:50 p.m. PST

I did some small 25mm torsos and legs using two part hardware store epoxy. It was the blue and yellow knead together type

Asteroid X08 Jul 2020 9:26 a.m. PST

Thanks guys!

Waco Joe, that is Green Stuff ( link )

John Leahy have you ever tried using resin with Oyumaru?

DyeHard08 Jul 2020 2:59 p.m. PST

Kneadatite A.K.A. Green-stuff is an
Epoxy putty:

Most will mix both with each other and in slightly different ratios to get a range of stiffness and effects.
The one so many folks call "Green Stuff" is Kneadatite green/yellow (I think this was a plumber's putty)
Oddly keeping the same nickname as a much older sculpting putty "Green Stuff" which was a form on Bondo auto-body putty (Not an epoxy). See also Squadron Green putty and white putty

The prime source of Kneadatite is:
polymeric systems


There are simply tons of formulation, so I suggest trying a few and finding one that fits your needs before trying to bend them.

That said I think this type: "Brown Stuff" or "Aluminium epoxy" or "Gas Tank repair" works well for these push molds:

Here are a few random videos of epoxy putty in used with the Oyumaru thermo-plastic mold. The second one is a three-part mold.
YouTube link

YouTube link

This is another nice reference page for epoxy putty:

Thresher0109 Jul 2020 8:33 a.m. PST

Thanks for all the info and links.

wardog12 Jul 2020 11:57 a.m. PST

same question as wymers above
has any one tried casting resin in these molds?

DyeHard12 Jul 2020 2:07 p.m. PST

I have not tried to pour into this stuff yet.
Only press casting.

But there is nothing to make me think you would have any problem beyond making a mold that will hold a fluid.

I see a potential problem if you use mold release agent, as it would contaminate the Oyumaru. But reheating the Oyumaru after the resin has cured should allow you to pull it free from the casting without release agent.

John Leahy Sponsoring Member of TMP13 Jul 2020 5:36 p.m. PST

Hi, I have not tried resin. I'd likely just create actual RTV injection molds if I was going to use resin.



John Leahy Sponsoring Member of TMP19 Sep 2020 11:30 a.m. PST

UPDATE! I have discovered that composimold is another molding product than can be reused. This you microwave to melt it. It also can be used with Resin. It then can be melted down and reused. I'm going to pick up some of this.



Asteroid X20 Sep 2020 7:10 p.m. PST

It might be easier to pour resin.

I haven't had a lot of time to play with the oyumaru but it seems you have to compress the mould pretty good to get a decent two part moulding.

Sebastian Palmer02 Oct 2020 2:53 a.m. PST

I like this thread! I'm fresh from my first period of silicone mould making and resin casting. That cost a lot and was very time consuming.

I too have seen several of those YouTube videos of people using the 'blue stuff', and I'm definitely going to give it a go. So thanks to those who've posted useful links here.

It seems most folk I've seen doing this and making stuff got 28mm scale. I'd be making mostly very small parts for detailing 1/72 WWII vehicle models. Has anyone here used blue stuff in smaller scales than chunky 28mm?

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