# 3D Printing > General 3D Printing Discussion >  Creating molds from 3D Printing?

## sparkdaddychad

Has anybody ever experimented with creating molds via 3D Printing and then pouring liquids into the mold to create the object?  Kind of the inverse of what we traditionally think of when 3DP'ing.

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## donny

I've heard of people doing this to make metal objects.  Since there is no reliable way of printing in Metal at home, people print plastic molds and then use those molds to make metal objects.  Not the easiest or the best way, but it's definitely more affordable. than printing in Metal.

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## sparkdaddychad

Im going to give it a whirl.  Im thinking that I can take my model, then create a box around it, then delete the model from the inside of the box which should then give me my mold.  Only thing that i am worried about is overhang inside of the box being that I do not want any infill where the model previously was.  Im guessing that I will also have to design some holes in the top/bottom of the mold in order to give me a place to pour the liquid into the mold and also to help with bubbles, etc.

I will report back what I find out, seems like a fun challenge to tackle.

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## DangerousThing

Look on the internet about lost wax molding.

i would, once I've gotten my object perfected, use a water-soluble filament that can be flushed out. Or you could use PLA and really heat the mold up to melt it out.

please keep us informed as to your progress. Maybe I'll need to make something in metal someday.

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## jzatopa

Here is a little on lost PLA casting

Here is a video of it being used in injection modling.




The same process would apply for something such as cast resin/plaster/cement molding except you might have to make larger pour holes and vibrate it to get the air bubbles out.

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## IanJohnson

3D printing is really good for making custom mold boxes.  Model the thing you want molded built into the bottom of a cup which is shaped around the object with the walls only as far away as needed.  Then fill the cup with silicone.  Pull the silicone out and that's your mold.  It uses only as much silicone as you need, rather than wasting a bunch filling up the corners of a square mold box.  It's good for things you want to produce and would like to have many copies of the same mold.  So print a mold that you will use to make molds.  Some times you can pour and cure a mold faster than you can print one.

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## dave21740

I've thought about using food grade silicone to make a mold of a printed object, and use the mold to make chocolates. An actual chocolate printer would be more straightforward, but there's no way I can justify the cost. A mold would be a much cheaper entry to that sort of hobby.

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## navkram

I have done this a couple ways, I have printed the mold and cast that i have printed the part made a silicone mold off that *nd cast parts, the problem is most parts it is not required for them to be cast solid, the resin material is not cheap, and weight is a factor.
I have made a small desktop rotational casting machine that will allow you to cast hollow resin parts. Check out the video http://rotomaak.com
I print prototype models for a large rotational plastic company this way i print one original make a mold and make reproduc5ions

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## Valter

Great topic.
I'd like to know if someone here are working with mold/cast resin from a 3d SLA printed scultures? Will resin models printed work fine to make a silicon mold and casting resin prodution? I'm thinking to sell my 3D characters models and I'm need more informations about process and method.
Should I print a 3D character or print a mold of the 3d character?

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## navkram

> Great topic.
> I'd like to know if someone here are working with mold/cast resin from a 3d SLA printed scultures? Will resin models printed work fine to make a silicon mold and casting resin prodution? I'm thinking to sell my 3D characters models and I'm need more informations about process and method.
> Should I print a 3D character or print a mold of the 3d character?


Valter,
I have done both, if there is undercut detail in the figure you will have to go with a silicon mold pulled from a original, the reason for this is the silicon will allow you to be able to remove the part if there is alot of undercuts etc. it will stretch to be able to remove cast part. With a silicon mold you can re-use it many times and its pretty durable compared to a hard printed mold.  If it is a simple (example hollow easter bunny) that has little detail like arms etc. you could print the mold, but with a printed mold it is rigid and have to think ahead on getting part out.
check out  http://alumilite.com for some great mold tutorials. 
the process is really dependent on the figure and end use. I have a model of a infants head from a customer that makes dolls, to cast this solid is not really feasible since the end product would weight around 5 pounds. so in this case my rotational casting machine fits perfectly to cast hollow parts. now the head weights ounces instead of pounds and functions perfectly for its intended use.

in short you should print the original vapor smooth or post process it however to get want you want and make a silicon mold of it.

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## Valter

> Valter,
> I have done both, if there is undercut detail in the figure you will have to go with a silicon mold pulled from a original, the reason for this is the silicon will allow you to be able to remove the part if there is alot of undercuts etc. it will stretch to be able to remove cast part. With a silicon mold you can re-use it many times and its pretty durable compared to a hard printed mold.  If it is a simple (example hollow easter bunny) that has little detail like arms etc. you could print the mold, but with a printed mold it is rigid and have to think ahead on getting part out.
> check out  http://alumilite.com for some great mold tutorials. 
> the process is really dependent on the figure and end use. I have a model of a infants head from a customer that makes dolls, to cast this solid is not really feasible since the end product would weight around 5 pounds. so in this case my rotational casting machine fits perfectly to cast hollow parts. now the head weights ounces instead of pounds and functions perfectly for its intended use.
> 
> in short you should print the original vapor smooth or post process it however to get want you want and make a silicon mold of it.


Thank you very much.

My 3D models (most them) are complex. So I'm thinking that a silicon mold will be the only way to get a good copy. navkram, just for curiosity. How many copies your silicon mold support with a sculpture with 20 cm tall? Polyester, polyurethane, vynilester Resin?
Thanks again. Excuse my english.

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## navkram

You should be able to get a couple 100 copies depending on how careful you are with the molds and how well you take care of them (mold release) i am using a 2 part urethane air cure resin from alumilite.com

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## Valter

Thanks so much navkram.

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## awerby

I imagine some of the flexible materials the Objet uses could work as molds directly. But it would probably be more cost-effective to print a positive form and make molds from it, since you could make multiple molds from each model. I like the idea of 3D-printed mold boxes, though; that could definitely minimize the use of expensive mold rubber. 

Andrew Werby
www.computersculpture.com

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## navkram

> I imagine some of the flexible materials the Objet uses could work as molds directly. But it would probably be more cost-effective to print a positive form and make molds from it, since you could make multiple molds from each model. I like the idea of 3D-printed mold boxes, though; that could definitely minimize the use of expensive mold rubber. 
> 
> Andrew Werby
> www.computersculpture.com


I dont know why I never thought about using a flexible material, I have been wanting to get some this just made a reason to get some. I will update once I have some.

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## Valter

It's a interresting point. If this soft material from objet has a good mechanical and chemical resistance like as silicon rubber. Will be a great option. Otherwise. Why not make a silicon copy from 3d printed mold

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## MeoWorks

Check out my guide here on how to make a cheap waste mold and transferring your 3D print to wax for further finishing. 

http://www.statueforum.com/showthread.php?t=142321

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## navkram

> Check out my guide here on how to make a cheap waste mold and transferring your 3D print to wax for further finishing. 
> 
> http://www.statueforum.com/showthread.php?t=142321


Great tutorial, I done this but was not happy with the results, too many air pockets.  What is the advanrtage adding the glycerine?

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## Davo

Or you can just print the mold directly with silicone.

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## navkram

> Or you can just print the mold directly with silicone.


Davo,

please tell/show printing the silicone mold. sounds interesting.

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## Davo

We've printed gaskets with RTV Silicone. We don't have a video, but I'll request one. 

We are working on various fast-curing Silicones to speed the printing process - otherwise it's a slow print (waiting for each layer to set), or a sloppy print.

Our machines can print in just about any emulsifiable extrudable that is thick enough that it doesn't just run out of the tube and across the build platform. Essentially from the consistency of mayonnaise through precious metal clays. We have videos of our machines printing in clay, plasticine, plah-doh and sugru (rubber). The sugru is probably the closest consistency to RTV of anything we've filmed.

Anyway, the idea is to just print the mold, rather than printing a sample piece and then building a mold around it.

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## awerby

> Great tutorial, I done this but was not happy with the results, too many air pockets.  What is the advanrtage adding the glycerine?


If you really can't get proper 2-component mold rubber, silicone caulk can work as an inferior substitute. But as Navkram points out, the substance is too thick to avoid entraining air next to the surface of the model. It's better to at least use real silicone mold rubber as a first coat, painted on and allowed to cure, to get the detail, before applying caulk as a second coat (although you can also use a thickened mixture of the 2-component rubber). It not only picks up the details without bubbles, but releases much better than the caulk, which was formulated for adhesion, not removal.

Andrew Werby
Juxtamorph.com

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## cipher0

I don't understand how you can use printed plastic molds and pour molten metal, etc. in them. Won't the temperature of the molten metal cause the plastic mold to melt itself?

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## 3dkarma

There's an scad program you can download from thingiverse that will generate a two-part mold from your model.  I've successfully used this to create something with sugru.  The original designer has cast pieces with wax, Knox gelatin, Oogoo and chocolate and has made casting tips and notes on metal casting via lost PLA available.

Parametric two-part mold generator for OpenSCAD

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## jzatopa

IF you need to do a lot of molding you may want to check out this roto-mold that looks like it will be on kickstarter soon.  RotoMAAK

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## awerby

Cipher, there are many things that can be poured into plastic and rubber molds that aren't too hot. Yes, most molten metals would be destructive to a plastic mold, but an indirect method can be used if one wants to produce metal parts. One of these is lost wax (assuming wax was cast in the mold). The casting is encased in an outer mold made from plaster and silica powder which is heated in a kiln until the wax is burned away, then metal is introduced into the cavity. Then the plaster is washed away, so the metal object remains. The "lost PLA" method mentioned above is a variant on this technique, with a positive PLA model used instead of a wax one. 

Andrew Werby
www.computersculpture.com

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## python

excuse my english, i dont understand. Is there maybe a video of that process?

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## 3dkarma

> excuse my english, i dont understand. Is there maybe a video of that process?


Do you mean the mold creation process, or one of the others in the link?  I'm not aware of any videos of the mold creation process, but the instructions on the thingiverse page are fairly detailed.  If these aren't clear or you need further help, feel free to post your questions here or on the thingiverse page.  I'm not the creator of the script, but I'll help where I can.

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## python

sorry. i didnt understand how the indirect method with wax or pla works.

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## 3dkarma

> sorry. i didnt understand how the indirect method with wax or pla works.


Ah, OK.  There's a good writeup (with lots of pictures and video) of lost PLA casting here: http://3dtopo.com/lostPLA/ 

Edit: Comprehensive writeup of lost ABS casting here: http://jason-webb.info/2012/11/lost-...minum-casting/

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## python

Thanks     !

I wonder if this can also be done with uv-sensitive resin prints.

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## navkram

> Ah, OK.  There's a good writeup (with lots of pictures and video) of lost PLA casting here: http://3dtopo.com/lostPLA/ 
> 
> Edit: Comprehensive writeup of lost ABS casting here: http://jason-webb.info/2012/11/lost-...minum-casting/


Thank you for these links great information in both of them.

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## navkram

> IF you need to do a lot of molding you may want to check out this roto-mold that looks like it will be on kickstarter soon. RotoMAAK


thank you Jzatopa, for this link.

Being new to this forum but not new to 3d printing and mold making I did not want to make it feel I was only spamming the forum, and hopefully can contribute to this forum.

I am the creator and builder of the RotoMAAK, we have done lots of testing and prototyping to get a solid machine, we are finishing up the final info for the kickstart campaign.

this was developed out of a need that I had, a customer came to me and wanted a scale model sample of a large rotational cast plastic part to justify the change to a $80,000 mold, I printed a scale model of the part close to 12 hr print time for the first one, they past this on to their customer for the engineering department to show the salesmen what the proposed changes were going to be. once in the hands of the sales department they got the green light to make the changes. meanwhile the sales department loved the model and request 10 more "salesman" samples to allow the sales to show their customers since the actual part was the size of truck bed and it has been easier for them to sell the product if the customer can hold the part.

to reproduce 10 samples on my printer would take min. 120 hours of print time not including failed prints etc. so I made a silicon mold of the printed part and developed the rotomaak to cast hollow parts, I could have cast the part solid but that was just a waste of resin, 5 lbs of resin compared to a couple ounces. 

I took the first machine to the detroit makers faire to just have sitting the running because it looks cool spinning. I got tremendous response from other makers on what niche this machine could fill. so with the support of a few key companies I proceeded to make changes and now we are very close for release.

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## Larry

> Has anybody ever experimented with creating molds via 3D Printing and then pouring liquids into the mold to create the object?  Kind of the inverse of what we traditionally think of when 3DP'ing.



This is actually what the European Space observatory is doing with 3D printing.  They make molds of parts for their telescopes with 3D printers and then pour aluminum into those molds.

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## mechadense

I tried printing flexible PLA as a mold for PU. I used silicon spray as release agent. => The mold got destroyed after only one use.
My grey soft PLA behaved like chewing gum :S very little shape memory.

For small quick and cheap stuff I now use ogoo (acetic silicone + corn starch). It sticks on PLA while wet and goes off easily when dry - just perfect.
I used wax based release agent to quickly make around a dozen PU copies from a single mold from a specific PLA part (PLA positive -> ogoo negative -> PU positive)
An other release agent might be better (less viscous)

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## LambdaFF

There is a quite simple technic that you can use. With electro plating you can create a metallic layer of zinc or copper or nickel on you part. If you make the deposition thick enough it can make a mold. You will need to put some conductive paint on your plastic part first as it is not conductive.
Conductive paint : ~14€/400mL.
Copper Sulfate : ~20€/1kg
Car battery, a pair of crocodile pincers.
And then you remove the plastic by heating. It's easier if it is wax, but perhaps it would work as well if you do it with a soluble material like the ones for support.
However, it only works if the end material is supple enough to be extracted. Otherwise you need to cut the design to make separate mold parts.
CATIA has excellent molding design tools.

On a different note, for the release agent. If your part is big enough, most composite manufacturers cover their big (read costly) molds with teflon adhesive or a teflon coating. I never saw it in Europe but in China you can find it in spray cans.

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