5 Easy Steps to 3D Print a Ukulele: A Dual Extrusion Case Study

3D printing dual extrusion

Airwolf 3D Wolfpack Team Member Eva Wolf shares her latest project: A custom-made ukulele that shows off the new AXIOM 20’s dual extrusion 3D printing capabilities.

Yes, by now many of us have seen a dual head 3D printer in action. Or perhaps you have noticed a cool two-color, 3D-printed part and asked yourself, “How did they do that? How did they design a model for dual heads? Can I learn how to use dual extruders? How does one even begin to slice such a part for running two extruders in tandem?”


I am here to tell you that you too can easily design and 3D print an amazing part with two materials. 3D printing with multiple materials is a lot less complicated than you might think.

The 3D Printer Dual Extruder Advantage

There are several benefits to having two print heads. One 3D printer dual extruder advantage is the ability to print with a dissolvable support material. For example, nozzle no. 1 can print the model in ABS and nozzle no. 2 will print the dissolvable support to hold up overhangs, such as a cross bridge between two towers. Imagine this: Without support, nozzle no. 1 would attempt to print a bridge by depositing hot gooey plastic in mid-air and, ultimately, it would just drip down and fall on the print bed. Can you imagine such a hot mess? Fortunately, nozzle no. 2 is there to help and will be printing a foundation of support material so that nozzle no. 1 will have a nice solid platform to deposit and build the bridge.


Another 3D printer dual extruder advantage is the ability to print one solid object in two different colors. Take for instance this red and black ball bearing. It is 3D printed in red AND black ABS filament using two print heads simultaneously and as one single component.


In this case study, we will demonstrate how easy it is to 3D print a ukulele in two different colors of ABS filament and how to put your dual extruders to work.


5 Steps To Dual Extrusion 3D Printing

This case study will walk you through the five easy steps of 3D printing a dual color ukulele. Before we get started, wrap your head around the fact that 3D printing a part with two materials is actually like printing two “separate” parts at once. To quickly demonstrate this, we start with a pre-existing .STL model of a ukulele that is already broken up into two components. Steps include: Importing the .STL model components into a CAD software, aligning the components, exporting positioned components as individual “parts,” importing the two parts into 3D printer dual extruder software and slicing for a dual extrusion printer. But enough of that complicated technical jargon — let’s get started!

When the AXIOM 20 gave us the capability to 3D print parts as big as 20 inches tall, it opened up a whole new world of bigger possibilities. Seeing as how a couple of us at Airwolf 3D recently started playing the ukulele and considering that the standard height of a soprano ukulele is about 20 inches, it seemed natural to 3D print a dual color full size ukulele in one print job!


We found this well-designed ukulele on Thingiverse: “Nukulele” was designed by Jeremy Throop, a.k.a. “Rips” and, as the title claims, it is indeed printable without any support material. This is a good thing because the last thing you want to do is to try to remove support material from the inside of a small instrument’s very small soundhole! Rips, the designer, cleverly designed inner sloping arches to eliminate any need for internal support and the best part is, it can be 3D printed standing up and make full use of the height capabilities of the AXIOM 20!

Rips designed the ukulele to be 3D printed in parts and then assembled to a full-size functional instrument because up until now the public has been limited to the much smaller print envelope of current 3D printers. However, the 20-inch build height of the AXIOM 20 eliminates that need to break it into small parts and allows us to 3D print a full-size soprano ukulele in one swoop. So roll up your sleeves and download the neck and body of Rip’s “Nukele.”


“Nukulele” by Rips: www.thingiverse.com/thing:691993

Step 1: Importing the .STL model components into a CAD software

After you have downloaded the two STLs (neck and body), import them into your CAD software. In this case I will demonstrate with TinkerCAD. Hint: If you would like to skip the design of steps 1 and 2, you can go straight to Step 3 and use the existing aligned TinkerCad model here: Two Color Uke.

Open up TinkerCAD.com in your browser and start a new project. Next, import Rip’s STL’s of the neck and body.


Step 2: Aligning and Positioning the Parts for Dual Extrusion 3D Printing

You will notice that the neck and body parts might overlap and sit level on the same plane. Imagine that this is the floor of the 3D printer bed.


Rips has added a nice “joint” to this uke. A “joint” is a simple woodworking term and, in relation to ukuleles, usually refers to where the neck meets the body of the instrument. You will raise and position the neck so that it is situated higher and falls into perfect alignment with the body, using the joint as a guide.


Now that the two parts are positioned in their correct printing locations, you are ready to export as separate STL’s.

Step 3: Exporting The Parts In Proper 3D Printing Position

Select one at at a time and export for 3D printing. In this example we have selected the neck and downloaded it for 3D printing.


When you download make sure to check the box to only download the selected shape!


When you download the part, the STL will “remember” the exact position of the neck in relation to the body and its location on the printing plane.

Step 4: Using 3D Printer Dual Extruder Software APEX

Download APEX from Airwolf3D.com and install it on your computer. APEX is a great 3D printer dual extruder software that is capable of generating complex gCode for two print heads. Open up APEX and load the two aligned parts (neck and body) like you would any parts (hint: you can select two or more files to import at once).

Step 5: Slicing The Parts For Dual Extrusion 3D Printing

After we import both parts, they will rest on the flat 3D printing surface. Don’t worry, they just need a little help remembering their true printing location on the printing plane.


Before doing anything else, make sure that you have selected the correct 3D printer in settings. In this case you will select a dual extruder 3D printer, such as the AXIOM 20 or the AXIOM Dual Direct Drive. One of the many great features of APEX software is that it already comes loaded with simplified dual extruder profiles for various 3D printer models.


It is also important to select the right material. For example, in the filaments menu you will find a dropdown list of materials. As of this date (12/11/16) the drop down list of materials shows 27 materials. Select “ABS Dual Color.”


Next, select the neck part and right click. A menu will appear and you will select “Dual Extrusion Merge.”


The two parts will align and “remember” their location as it relates to each other and on the printing plane.


You are ready to save your gCode and 3D print your first dual extruder part.

Taking Dual Extrusion to New Limits

As you can see in the following example, we took it a step further and broke up the body and neck STL’s into more colorful components. While in tinkerCAD, we split the neck .STL into two parts to add a little more color and variation to the overall look and feel.

We separate the headstock (top yellow flat piece at the end of the neck that holds the tuning pegs and commonly displays the ukulele brand logo) from the neck. We also separated the orange tie bar bridge from the body of the uke so that it might resemble a traditional wood ukulele. Then in TinkerCad, we selected and grouped the yellow headstock and body as one “part” and exported them as one STL. We did the same single STL export with the orange neck and bridge components. To see this 3D-printed ukulele in action and hear its beautiful sound quality, click here for a video.

You can download the free STL file for this dual color Uke here on watertight.com.


If you want to build this ukulele yourself, you will need only two supplies. The first are machine heads. These are tuning pegs that work using a gearing system to turn the string post. In our orange and yellow uke, we use BQLZR Ukulele 2R2L Chrome Geared Machine Heads with Mounting Screws.” You can find these for about $9.50.


Second, you will need some ukulele strings, such as Aquila Soprano Ukulele Strings Nylgut Regular C Tuning 4U. These come is a set of 4 and offer better sound quality than traditional nylon strings for the low cost of $7.00.


Finally, you will need to tune your ukulele. If you are new to music, don’t worry! You can download many free ukulele tuners and chord chart apps for your smartphone or tablet.

For tuning my uke, I recommend a free app that goes by the name, Simple Ukulele Tuner – Free Chromatic Tuner By Ullrich Vormbrock.

Congratulations, you are now a luthier (the term given to one who makes guitars and ukuleles)!

If you are interested in learning how to play, you can find the chords tab charts for many popular songs on this app Tabs & Chords HD by Ultimate Guitar.

Aloha and mahalo!


See (and hear!) the 3D-printed ukulele in action!