The Mini Metal Maker: An Exclusive Look at the World’s 1st Desktop 3D Printer for Metal

They're among us. And their numbers are growing. They are the maker culture.

These do-it-yourself 3D printing aficionados are frequently found working busily in their makerspaces. These workspaces dedicated to creation might contain many interesting gadgets and tools, like the Stratasys (NASDAQ: SSYS  ) MakerBot, Autodesk's 3D modeling software, or 3D Systems' new Sense.

Makers, more than anyone, realize their space will likely evolve over time. Especially one maker in Colorado: David Hartkop, creator of the just-unveiled Mini Metal Maker.

The Mini Metal Maker. Source: Mini Metal Maker Indiegogo campaign.

Hartkop believes the new invention will fit right into to the maker culture, filling an obvious void that finally gives the craft and maker community a way to print metal objects in smaller spaces.

What's Hartkop's target market price for the new 3D printer? Just $500.

Sure, the Mini Metal Maker is still a work in progress. But it may also be a first step of many in a new direction for do-it-yourself 3D printing.

An exclusive look
Curious about Hartkop's invention (and as a Colorado resident myself), I traveled down to Pueblo, Colo., to meet with Hartkop and get my hands on the new printer.

So, what exactly is the Mini Metal Maker? And what makes it unique? Hartkop explains.

Still in the prototype stages, Hartkop says he is only scratching the surface with his invention, and fully intends to see his creation through to market. On his just-launched Indiegogo campaign Hartkop said the "Mini Metal Maker is a game-changer in the world of do-it-yourself 3-D printing."

David Hartkop (on left) talks in his office to author about how the Mini Metal Maker shortens the process of making objects with metal clay.

The creator
Who is David Hartkop? His resume is as interesting as his creation. With a degree in film from Loyola Marymount University, Hartkop has dabbled in film and special effects, even working on effects in videos that featured xZibit, Eminem, BoneThugs, and Nelly. He has also designed the world's first solar-powered coffee roasting system and went on to co-found Solar Roast Coffee with his brother Mike. Today, beyond his work over at the just-franchised Solar Roast, he also works part-time for the Pueblo City-County Library district.

As it turns out, the Pueblo library is home to one of Stratasys' MakerBots, which prints 3D plastic objects. Hartkop actually used the MakerBot to help him print some of the pieces necessary for the original prototype of the Mini Metal Maker. MakerBot, in fact, can take the credit for much of Hartkop's inspiration to create the Mini Metal Maker.

The sketch shown in the video above shows a potential use of the Mini Metal Maker in electrical applications, with the help of dielectric clay, to create an electrical transformer (using copper, ceramic, and iron) or even an electrical motor (including the conductors, insulators, and bearings).

The details
The Mini Metal Maker uses metal clay as inputs. Once the metal clay is printed, and after "these clay objects air-dry, they are fired in a kiln to produce beautiful solid metal objects of high purity and precision," Hartkop explained on his Indiegogo campaign site.

For those not familiar with metal clay and its capabilities, Hartkop elaborated on its properties:

The metal clay suppliers state in the info about their clay that once it is fired, the appropriate stamp for metal purity is '.999' or 99.9% pure. This mostly applies to use with high value fine metals like gold and silver, but is a good indicator of how pure the metal left behind is, once you fire metal clay objects.

So once the kiln process is complete, the end result of the 3D printer's output is a very durable metal object built to a specified digital file's standard.

As some hobbyists familiar with metal clay might point out, it's also possible to use the lost wax method to make metal objects if you are going to be using a kiln anyway. But, as Hartkop explained to me, the lost wax method is more complex:

  1. Attach sprues (small wax stems)
  2. Cast in plaster-like material, let dry
  3. Wax burn-out in kiln
  4. Cast metal (with torch, crucible, and centrifuge)
  5. Cast removal
  6. Sprue removal (with saw and wire cutters)
  7. Clean up (with a file and dentist tools)
  8. Surface finish
Using the Mini Metal Maker, the process is much shorter:
  1. Print metal clay
  2. Clean up
  3. Fire in kiln
  4. Clean up and surface finish

That said, the kiln process is probably the biggest drawback to the Mini Metal Maker's approach to printing metal at home. Sure, the process of making metal at home is shorter with the Mini Metal Maker. But Mini Metal Maker owners will be required to have a kiln to fire the printed clay.

Another challenge Hartkop listed will be getting the software to account for the shrinkages that occur in metal clay when it is fired. Different forms of clay have different levels of shrinkages. The software will have to adjust the print of the clay to account for the shrinkage that will occur when the clay is fired.

What kind of objects could be printed with the printer?

Is the Mini Metal Maker safe for at home use? Hartkop says it is.

Just how accurate is the Mini Metal Maker? Hartkop believes he can get extrusion precision down to 200 microns -- an ambitious undertaking, considering how close it is to the popular MakerBot resolution capability of 100 microns.

What's next for the Mini Metal Maker?
As seen on his Indiegogo campaign, Hartkop has laid out some ambitious next steps to take when he gets the required fundraising:

  1. Refine the metal clay recipe for each of five different clay types: Copper, Bronze, Steel, Silver & Gold.
  2. Refine our high-pressure extruder design. We currently have a reliable extrusion trace at around 0.5mm but believe this can be reduced to 200 microns.
  3. Add a second print head for use with additional metal clays or support material.
  4. Optimize the integrated motor carriage design so that it can be easily printed on low cost printers such as the Makerbot and RepRap.
  5. Refine custom firmware for the printer to further optimize printing for clay.
  6. Create the Mini Metal Forge software environment in order to foster a good user experience, particularly for the non-technical craftsperson.
  7. Work with industrial partners to tool up for production of the machine with injection molding.

To wrap things up, I asked David to give me a 10,000-foot view of his long-term goals for the Mini Metal Maker. He didn't hold back.

In the Mini Metal Maker, Hartkop has opened the door to a missing link in do-it-yourself 3D printing: metal. I think his device has huge potential.

Will it challenge existing 3D printing products (like the MakerBot) that are already popular in the do-it-yourself crowd? Not at all -- it's simply too different. But there's no reason a polished prototype selling for just $500 couldn't earn a spot right along with existing do-it-yourself 3D printers. As Hartkop explained to me, it's not a matter of one or the other; the Mini Metal Maker is a unique addition to existing do-it-yourself 3D printing technologies.

Going from prototype to finished product won't be easy. Particularly, Hartkop suggests that developing user friendly software and refining the nozzle and printing technology to get extrusion down to 200 microns will be a challenge. On the other hand, he feels confident he will be able to address these issues.

It's tough to say whether Hartkop will succeed in bringing his new 3D printer to market. But that isn't stopping the Indiegogo crowd that has nearly funded his entire project in less than a week after Hartkop's campaign launched. With 41 days left in the campaign, Harktop will likely raise far more funding than he set out to get.

One thing is for sure: The Mini Metal Maker is a step in a new direction for 3D printing.

"Welcome to the metal age of do-it-yourself 3D printing," Hartkop boldly proclaimed during the video posted on his Indiegogo campaign site.

Is there still money to be made in 3D printing?
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Read/Post Comments (25) | Recommend This Article (60)

Comments from our Foolish Readers

Help us keep this a respectfully Foolish area! This is a place for our readers to discuss, debate, and learn more about the Foolish investing topic you read about above. Help us keep it clean and safe. If you believe a comment is abusive or otherwise violates our Fool's Rules, please report it via the Report this Comment Report this Comment icon found on every comment.

  • Report this Comment On November 16, 2013, at 12:15 PM, tlwofford wrote:

    I don't know a whole lot about 3D printing, but I loved the article and how you worked the videos in! I think the videos are a big bonus.

  • Report this Comment On November 17, 2013, at 8:42 AM, VikingBear wrote:

    I'm glad this guy is on our side!

  • Report this Comment On November 17, 2013, at 8:48 AM, Mathman6577 wrote:

    Good thought provoking article. I think 3D printing is potentially a big growth area, much like energy production is because of innovation like fracking and horizontal drilling (probably bigger). I just read that GE will start making some parts of its jet engines by printing them. It might take some time but investing in 3D will pay off unless something gets in the way.

  • Report this Comment On November 18, 2013, at 4:47 AM, VikingBear wrote:

    What's to stop anyone with a metal printer from whipping up a batch of St. Gaudin's $20.00 gold pieces?

    Consider the former business models of both photography and 2D printers. At the home market level, the big profits were in photographic film, paper, and printer ink/toner powder.

    Who is making the 3D metal clays, and how do we get in on this aspect?

    How big a loupe will be necessary to distinguish sub-hundred micron differences in real or fake coins by numismatists and pawnbrokers?

    Do I hear government regulators baying in the distance?

    "Interesting Times."

  • Report this Comment On November 18, 2013, at 5:48 PM, CMFgdf wrote:

    Just to be clear, 3D printing of small metal objects using kiln finishing is not new. What may be new is bringing the process to your own workshop in an affordable way. However, one of the big questions to answer is tolerances and whether the "finished" object can be machined to the tolerance necessary for typical metal applications.

  • Report this Comment On November 18, 2013, at 8:02 PM, mogwan wrote:

    After reading through the process and the currently available materials: All of them: Gold, silver, copper, bronze, etc. have a low melting point and a very soft Rockwell hardness. This is the huge limiting factor.

    Modern firearms technology uses metal clay for a similar process called 'MIM' -metal injected metal. In this process a metal slurry is injected in insanely expensive molds to make parts very close in hardness to steel and requiring almost no final finishing. However, there is approx. 10% shrinkage when the molded metal cools. a $500 home system will never be able to do much more than plastics, soft metals and 'kiln processed' soft metals. The equipment being used for real 'breakthrough prototyping on an industrial scale costs $500K- $1 million or more and this is due to the complexity of the equipment.

    Comparing a $500 metal or plastic printing machine is like comparing a Dremel drill to a CAD/CNC machining facility. And the learning curve just to create CAD plans to 'print' anything more complex than a simple cube is an exhaustive full time job. I know this as i supported several Architecture firms in New York doing all drawings using Autocad. I am also a gunsmith so i do understand the nature of creating/replicating mechanical parts of this nature. I sincerely doubt we will see much more than a 'hobby device' in the sub- $10,000 space for at least the next 10-20 years.

  • Report this Comment On November 18, 2013, at 9:20 PM, awallejr wrote:

    I dunno you kind of lost me on the Kiln requirement heheh.

  • Report this Comment On November 18, 2013, at 11:07 PM, PatentGamer wrote:

    For the sake of the article's objectivity, the marketing folks listed on the crowd sourcing page are also Sparks (Tim and Chrissy) - any relation to the author?

  • Report this Comment On November 18, 2013, at 11:52 PM, marcin97 wrote:


    Good point.

    Scroll to the bottom.

  • Report this Comment On November 19, 2013, at 12:06 AM, constructive wrote:

    So maybe DDD, SSYS and all the others don't have much of a moat...

  • Report this Comment On November 19, 2013, at 12:20 AM, TMFDanielSparks wrote:


    Thanks for point that out! I actually wasn't aware of that until just now. He wasn't on the campaign at all before the interview.

    Here's the story:

    So I asked my brother, Tim, to help me film the interview. After giving him a call just now, he told me he had volunteered the day after the interview to managed David's twitter account (since my brother had done his own crowdfunding campaign, via KickStarter). My brother did it, he said, because he was inspired by the interview and wanted to help out.

    Anyways, he didn't have any monetary relationship with David or any access to the funds from the campaign. His wife, Chrissy, was also just helping with Twitter.

    He told me he would step down as a volunteer for the Indiegogo campaign after I told him about the confusion. He's already contacted David and asked him to remove his name from the campaign.

    Sorry about that! I can assure you it was purely objective Foolish analysis :).

  • Report this Comment On November 19, 2013, at 8:08 AM, pondee619 wrote:

    So, for the cost of a Saturday Night Special someone can "manufacture" an arsenal of untracable metal firearms? No licensed manufacturer and no serial numbers. David Hartkop, I'd like to introduce you to Alfred Nobel. Next up, the "Hartkop Peace Prize"?

  • Report this Comment On November 19, 2013, at 9:28 AM, neocolonialist wrote:

    I am curious how feasible it would be for this printer to be able to lay down copper in fine enough traces for circuit board applications. THAT could be a game changer.

  • Report this Comment On November 19, 2013, at 10:35 AM, TMFDanielSparks wrote:


    As long as you have the right metal clay and 200 microns is accurate enough, and a build volume of 2.3 inches x 2.3 inches x 2.3 inches (6 cm x 6 cm x 6 cm) in size is big enough to build the parts -- it could be a possibility. Though it may take a while...

  • Report this Comment On November 19, 2013, at 10:49 AM, neocolonialist wrote:


    So what, we now have to limit all activities to those which the small percentage of criminals and other nitwits amongst us might not be able to abuse? Best not to manufacture anything then I guess right? I mean, I am sure the makers of pressure cookers knew full well the dangers they were putting us all in! Anyway, its a whole lot easier and cheaper to steal guns than to try to manufacture them.

  • Report this Comment On November 19, 2013, at 11:23 AM, TMFRhino wrote:

    Fantastic work, Dan!

  • Report this Comment On November 19, 2013, at 11:37 AM, TMFDanielSparks wrote:

    Thanks Eric!

  • Report this Comment On November 19, 2013, at 11:49 AM, pondee619 wrote:


    That is why I compared him to Nobel. A machine that can "print" an arsenal of untracable firearms, in my opiniion, deserves some scrunity. Not sure it will be easier to steal the guns any more with a $500 "gun printer" on the market. What will that metalic clay cost?

  • Report this Comment On November 19, 2013, at 12:04 PM, vinny4130 wrote:

    I must admit I did not have the time review all videos so i may have missed this but i will ask anyway. What I read is, the metal clay can be printed very accurately but how accurate is the shrinkage factor after firing? it is somewhat misleading to say a part is accurate but still needs more steps to finish.

  • Report this Comment On November 19, 2013, at 12:15 PM, TMFDanielSparks wrote:


    Good question. Shrinkage varies by metal clay type. After reviewing the shrinkage of different metal clays, it looks like the average is about 15%.

    Hartkop plans to have software built to address for the shrinkage of different types of metal clays. This is why it doesn't make sense to get extrusion down to 100 microns -- instead, 200 microns is the goal.

    Keep in mind, this is the first prototype, which David didn't start working on until midway through the year. It was only to "demonstrate the concept" so he can raise the money to build the real thing that executes his full idea.

  • Report this Comment On November 19, 2013, at 3:06 PM, radred68 wrote:

    This machine will never and is not intended to be for making anything other than small objects, and using soft base metals there is no worry of making guns or other things as stated above. For someone that is trying to do a prototype of say a different type of watch movement or an chnage to some other internal workings, rather than have to have an industrial shop tool the part, it gives them the opportunity to see if the part will work in conjuction with others. I personally started following the make it bot years ago (when it was 5k plus to purchase). the applications are, of course nearly endless, but to think that a criminal will go through the process and time to make gun parts or anything is, in my eyes, pretty absurd. I think it's a great furthering of an already great product, makeit bots.

  • Report this Comment On November 19, 2013, at 6:13 PM, BOB7324 wrote:


    I am a dentist. A few companies are using systems similar to this. They use porcelain precipitation. Also, there are systems that mill metal. I am not sure the tolerences needed in dentistry, about 25 microns, are possible with this technique. It would be great to print something usable in the office in a reasonable amount of time.



  • Report this Comment On November 19, 2013, at 7:09 PM, mogwan wrote:

    Bob, to make a porcelain crown for instance: you would have to be able to 3D scan the wax impression (or a reverse plaster mold of the impression. 3D scanners= very expensive. Then translate the raw scan to a CAM program and produce an instruction set to drive the printer. Then you would need a material that could withstand the everyday wear & tear created by the human jaw... think you'll do this soon with a $500 printer?

    Any 'non-professional' person who has tried to master even the basics of a CAD software program would be baffled and seriously challenged to create 'anything' of use unless they were using a 'canned' instruction set. even these are difficult to modify w/o a fair amount of training.

    And porcelain precipitation is not similar...

  • Report this Comment On November 20, 2013, at 12:20 PM, extet wrote:

    What's the 3 stocks that will revolutionize TV? also what's the 179,000 dollar stock bet?

  • Report this Comment On November 21, 2013, at 8:27 AM, BillStruve wrote:

    This is an interesting application of our clay that has been on the market since 2008. Jewelers and craft folks usually form objects by hand from our BRONZclay, then dry them, and in the dry state can sand, drill, carve and make final adjustments quite easily. After firing in a kiln, the metal particles in the clay fuse into solid tin bronze. Unlike commercial bronze, which is an alloy of zinc and copper, tin-bronze is an ancient material that is strong, hard and tough. I look forward to working with David to perfect his process. My hat is off to him!

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