From 3d Printed Part to Metal, the Lost Pla/abs Method


Introduction: From 3d Printed Part to Metal, the Lost Pla/abs Method

  So You have your 3d printed part all finished up and its beautiful. Now what to do with it? I know turn it into a nice bronze casting that will be a forever keep sake.   Here I will demonstrate turning your 3d printed part from plastic into metal. Make sure you stay tuned for the video at the end of the instructable.

Step 1: Spruing Up, or Building a Yoda Tree...

The first thing we need to do is to sprue up the parts and create a tree for casting. Here I am taking the printed parts and attaching them to wax rods to build the tree. The wax and the printed parts will be burned out later in the process.

Step 2: The Completed Tree

This is the completed tree. When attaching the parts to your tree you need to watch the way the parts are oriented. You do not want to attach the wax in a way that there will be an air pocket formed above the wax rod when the metal is poured. The wax rod should be the highest point of the printed part when casting.

Step 3: Mixing and Pouring the Investment

Once you have your tree all done it is time to mix your investment. There are several makers of the investment powder so it is best to follow thier instructions on mixing and burn out times. I am using americast by Ranson and Randolph. Once the investment has been mixed it is placed into a vaccum chamber for 2 minutes to remove the air bubbles.  Its at this point a slite deviation is made from the traditional lost wax methods, generally the investment is poured into the flask and then vaccumed again but since the printed parts are hollow and contain small voids that could allow the investment to enter the part if placed under vaccum I instead  place the flask on a vibrating table and the investment is slowly poured in. The vibration causes the air bubbles to rise to the surface and not stick to your printed parts.

Step 4: The Burn Out Process

It is now time to burn out you invested parts. Care must be taken during this step otherwise all your hard work will go right down the drain. The burn out takes a long time to do properly (again follow the investment mfg directions)  I started my burn out at 200C and once that tempature was reached it was held for two hours, then the tempature was increased to 460C and again held for 2 hours. The final tempature was 740C and held for 4 hours before turning off the kiln and allowing it to cool slowly to 200C which is the flask casting tempature I decided on for this pour and choice of material to be cast.

Step 5: Melting and Pourning

I chose silicon bronze as the metal for this cast. It is very fluid when molten and very attractive when cast. The melting was done in my small propane fueled furnace. The melt time was about 20 minutes and at the end of the melt the surface was skimmed to remove any impurities and then quickly poured into the flask and allowed to cool before quenchig in water to cool and remove most of the investment. In the picture you can seeall the little ears on the yoda busts, a great sign of a succesful cast.

Step 6: The Finished Product and Video

Well if all went according to plan you should be staring at your nice new casting. Here is the video that I promised, If you decide you would like to try your hand at investment casting please please please be careful. Working with molten metal is very dangerous, requires special safety equipment and lots of planning. If you have any questions please let me know and I will do my best to answer them for you.                     



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    20 Discussions

    When you burn out the PLA in your kiln does it contaminate the kiln in any way? I will be using a glass casting kiln and do not want to ruin the kiln with plastic residue.

    In the past I have worked with Precious metal clay, it is small particles of precious metal suspended in a binder, much like metal filled pla is 80% metal. Could you fire a metal filled pla and burn out the pla leaving just the metal form?

    1 reply

    Found an answer yet? This does seem like an original strategy!

    Will this method work with casting iron? All I see on the internet so far is every metal but steel which is very useful but alas, it aint steel. I don't mean stainless steel I mean just cast iron.

    4 replies

    I would imagine so, iron has a much higher melting point than bronze so your metal would be hotter than his and therefore burn out the plastic easier

    FYI, the plastic is burnt out before the metal is poured in. Thus the part with the kiln. Iron can be done, but requires a more robust furnace and crucible. We are talking around 3000+ degrees vs 2200 degrees F.

    If you use an investment for platinum and laymold filament you should be able too. Im going to try it soon, and will put up a video on my yt channel when i do.

    Ah man awesome! :D I can't wait to see the video. I hope it's a success. Thank you for the reply too. Wishing you the best of luck and has fingers crossed :D If we can lost investment cast any metal just thing of the possibilities. I honestly think it will take 3D printing to a whole new level for the home hobbyist.

    Just a heads up. is now selling spools of machineable-wax filament that is compatible with standard desktop 3D printers. Burns out much cleaner than any plastic.


    3 years ago

    I need a small vibrating table. What would you recommend?

    Nice work!

    I am making a one off custom manifold for a micro car that I am restoring.

    I have questions about the burn out process.

    I see you are burning out ABS, I have printed my model in ABS as well. burning in a kiln (as I have also planned) do you get a good burnout and did you experience any fire in the kiln?

    Nobody really details that part of the process. I'm looking for times, temps, fires, smoke and cleanup info.

    I have an old Dyna-kiln N90 that I purchased especially for this project but I was looking to find some examples of what to expect or helpful tips.


    1 reply

    the abs will stink up a city block. I would recommend you use pla instead. No fire in the kiln that I am aware of.
    The time for burn out its according to flask size but you would start with the kiln preheated to 260c and end at 730c What size flask would you be using?? Plasti cast is the best investment I have found so far.
    I have been casting alot of pla parts lately. Will be posting new video on youtube soon showing things in a bit more detal and with changes to how I do things to get the best results. You can e mail me at with any questions.

    I guess I should be shopping fro a PID for my Kiln then yeah?

    Would you consider doing custom castings from my STL or 3D prints in brass or bronze? I don't have a foundry or the common sense to use one. LOL



    Geek design, I guess it really depends on what your doing. but listen to the steps it takes to do the silicone mold method.
    Print a master part, make a silicone mold, inject the mold with wax, or just print 10 on a printer...I can see going the silicone mold for a 100 parts but not for 10. The silicone is expensive, takes time to cure, plus your time to inject the wax. Printing won out for this casting session by a long shot....

    Hi mate, always loving the Yoda in any form ;) but wouldn't be easier, faster and cheaper to print one 3D model in plastic, make rubber mold out of it and then make multiple wax patterns for metal casting? Wax is cheaper and you'll get more patterns faster rather to print every single one out...just a thought...

    Size wise you loose about 1% due to shrinkage of the metal as it cools, but you capture every single line on the printed part in fine detail.

    very very cool, how accurately do the metal casts compare to the original plastic prints? i am guessing(though it seems pretty obvious) that the plastic prints are destroyed in this casting process so if you mess it up and the cast comes out wrong you must print again.

    oldmicah, its a standard ceramics type kiln fitted with a digital temp controler, sprue down, elevated over catch pan. I have yet to find much in the catch pan after burn out so I wonder if ti is really necessary...

    Awesome work. Did you use a standard ceramic kiln to burn out? And (ignorant question) did you place the investment sprue down so the plastic dripped out? Do you have it elevated with a catch pan..

    I haven't done this but am starting to think I ought to be looking for used kilns. :)