Metal Casting – 3D Printed ABS Molds to Be Eliminate With Acetone





Introduction: Metal Casting – 3D Printed ABS Molds to Be Eliminate With Acetone

Hi everyone. My name is Joel Frax and I have been designing 3D printers since 2013. You can check mi most recent model on my web.

And for some time, I have been working for a way of creating metallic parts from my 3D printer. I wanted to find an easy, fast and simple way of getting metallic parts without a laser. I have been trying to print directly in tin, but it didn’t worked (you can check it on my post, but it’s in Spanish).

This is mi first post here in Instructables, but I would like to share my research. Here I will explain how to use low melting point alloys. In this example is an alloy of lead, bismuth and brass that melts at 140ºC.

So far I have found 2 methods for having metallic parts. I will share the first one while I translate the other:

Metal Casting – 3D printed ABS molds to be eliminate with acetone

This is the first way. And it’s very simple. The only thing you need to do is instead of printing your part, you print a mold of your part in ABS. Once you have it, you melt the metal and fill the mold with it. Then wait till metal is cold and submerge the mold with the part in acetone. This will melt the mold and you will get the metallic part. Let me try to explain it better with an example. In this case we will cast a Pikachu.

Step 1: Create the Mold

First we need to draw or download our part. But we don’t print it. What we do is drawing a cube to cover or part and we subtract the part to this cube. This will be our mold. It’s important to keep one part open so we can fill it. Another important thing is to have some place were to have extra material because when metal cools down it reduces the volume (I didn’t do it on mine …). Once we have this we print it. Resolution is a very important parameter, because otherwise we will have a lot of marks on our metallic part.

Step 2: Hold the Mold

Then we need to find a way of fixing the mold while we fill it. Is important to not hold it with the hand because melt metal can be dangerous … The mold of my picture is not the same as Pikachu but you will see a way of holding the molds.

Step 3: Melt the Metal

We need to melt the metal. In mi case I have used a blowtorch and a saucepan. Price for both components was less than 20 euros. You just need 140 deg, so is not complicate to get it. Even some electric ovens and cooking devices can get this temperature. We need to get a liquid metal so it can fill completely the mold.

Step 4: Fill the Mold

Filling the mold needs to be done slowly, so you allow the air inside the model to escape. Otherwise you will have bubbles. It’s also important to give some soft hits to the mold so we help this air to go out and the metal can fill everything. If you have any other advice about how to model please share with us ;)

Then you wait for the metal to cool down. It doesn’t take a lot of time, but it will depend of how big your part is.

Step 5: Dissolve It in Acetone

Then get a glass recipient (something that can be closed) and fill it with acetone. What you will have to do is submerge the mold inside the acetone. That will melt the ABS away and you will get the final metallic part. This process is slow.

Step 6: Final Result

And you will have your metallic part. Easy, right?

You can see lots more of information and pictures in my web (just in Spanish …). I would also like to apologies for my English level … Here you have the pictures of mi Pikachu:

If you do something like this following my method please share the results. I would love to see it ;)



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    Si pudieras hacer la pieza en parafina (cera) con tu impresora 3D, entonces podrias hacer un molde de yeso y después calentar la cera para que quede la cavidad y después vaciar el metal ahi, se llama lost wax casting.

    Interesting. I didn't think the plastic would hold its shape with molten metal in it, even a bismuth alloy...

    You can use acetone to smooth the lines inside the mold some. Its a simple process, and you are already half way set up for it. XP

    There's a more complicated method of using a 3d print for casting metal. Its also ancient and works really well. The process is called 'lost wax casting'. The idea is to make a meltable positive, then cover it in plaster, which can withstand heat of even melted silver.

    Then you stick it in an oven or a fire of some kind and melt out the positive. In this case your 3d print. You MIGHT be able to soak it in acetone but I don't k ow what that would do to the plaster..

    From there just use it as a mold

    3 replies

    Hi badideasrus. I know about smoothing the 3D prints with acetone. I have used it myself. The only thing that worries me is if acetone smooths it too much or not evenly (I can’t see the inside …). But I will try this way and posts the results on my web.

    Regarding about the other technique I wanted to try it too, but some people says that the “meltable positive” needs to be completely melted, but if you try to use PLA probably you will end up with rests of this PLA inside the mold unless you get a really high temperature. Do you know about any printing filament that will be completely melted? Or do you know a way of properly eliminate this PLA from the mold?

    I havent tried it out yet, sort of expensive and my printer is limited in how I can customize the settings (XYZPrinting 2.0 duo), but heres the link for wax filament

    Hi Harveyd. Have been really busy developing my last 3D
    printer, but definitely I should try this wax filament ;) Thanks for sharing.

    muy bien, and your english is fine, great and useful tut for lots of uses.

    1 reply

    I use
    SolidWorks for all my designs.

    That is really great! Is there a way to skip the use of acetone altogether by simply printing the mold in two halves that can be pinned and banded together?

    1 reply

    Hi CoreyR10,

    Yes there is a way of using a 2 part mold. I did some test about it and works fine. I have all the information on my web (, but unfortunately it’s in Spanish and I didn’t have time to translate it … (try using google translate, if not there is quite a lot of images so it’s easy to understand).

    In fact, you can see the result on the main image of this post. The heart next to the Pikachu has been modelled using this technique.

    Any question please let me know ;)

    Good stuff, this is another one for my list of projects. Does the moulding alloy have a proper name? I have scrap lead and aluminium lying around, but I don't want to melt either of these!

    1 reply

    It’s an alloy used for molds (typical lead soldiers for hobby). I have bought it here in a shop in Barcelona but I don’t know if it has a proper name (on the shop says Metal Model). The shop is Sagristan Products (, you can buy it online).

    The composition is 54% Lead, 35% Bismuth and 11% Brass.

    Very cool idea! Thank you for the translation to English!

    Interesting process. How long did your moulds take to dissolve?

    Have a great day! :-)

    1 reply

    Hi. This ABS mold took about 3 hours to dissolve, but because I removed manually part of the ABS when it was soft (use globes in a ventilated area because acetone is dangerous).

    I did some test with different ABS from different brands and some dissolved faster than others. So maybe you will have to try.

    This is so cool! What programs do you use to design your solid parts?

    1 reply

    I use SolidWorks. Is the same that I use to design my 3D printers. But
    any other soft will work. The only think you need to do is subtract a model
    (the future metal part) from a cube that will be the mold.

    I try to reduce the volume of the mold because otherwise it takes longer
    to dissolve in acetone.