3D printing 2 colors

How To: Print Two Colors With One Nozzle

Learn how to 3D print one part with two different colors with a single-extrusion 3D printer!

Alec Richter

July 2, 2019

Dual extrusion is a lot more commonplace than it used to be, but the different methods possible are as varied as ever. Some use articulating within the print head to change from nozzle to the other, some have multiple toolheads they switch back and forth from, some use one nozzle and purge out the old material, and some have two nozzles mounted to the same printhead. Each of these has their own set of advantages and disadvantages, but the biggest thing is that if your 3D printer doesn’t already utilize one of these, there’s some external cost involved in upgrading your printer to do more than one color or material in a print, unless you fake it.

There’s a couple different ways you can go about “dual extruding” your 3D prints: Separate Parts, Layer Swapping, First Layer Inlay, and Top Inlay.

Separate Parts

Separate Parts is exactly what it sounds like, design the base piece you want and have the secondary color be a set of pieces that slot into the first 3D print. This is specific to models where you can get straight insertions and don’t have odd angles to work around. Take for example, this Optimus Prime figure. This was originally modeled by ChaosCoreTech, but I have seriously modified the STLs for it. It was designed to work around a filament splicing system to use multiple colors in the same part, instead what I did was make each other color a separate piece that would easily slot over each other.

ChaosCoreTech's Optimus Prime has been modified to work with single extrusion printers without a filament splicer.

To demonstrate, let me show you how I designed the shift knob for my car: First I have the base piece here which I reverse engineered from the shift knob designed by Dingoboy71 on Thingiverse. The top and bottom sections are essentially the same, with some modification made for my car, which has an M8 threading for the shift knob instead of the M12 that the original was made for.

Dingoboy71's Shift Knob reverse engineered in Fusion360 for more precise modification.

Once I had the base remodeled, I started by creating a reference plane above the surface, and sketching out the shape I wanted using the various sketch tools, then I extruded it into the body of the knob the depth I wanted and kept it as a “New body” instead of joining or cutting it out like you might initially think.

The inlay before it has been cut out to match the contour of the knob.

Then I could use the modify>combine tool to find the intersection between the design and knob, keep that, and take this new body and subtract it from the knob.

The inlay has been cut out from the knob, but will fit it exactly, without any wiggle room.

This will give a perfect puzzle piece for the knob, but 3D printers just aren’t that precise, for zero clearance tolerancing, so instead what we can do is hide all the parts except the inlay, and use the push-pull tool to offset all the side faces inward. This value is going to be fairly specific for your 3D printer’s capabilities; for mine, 0.2 provides for a tough but solid fit.

Using the Push/Pull modifier is an easy way to add clearance tolerancing for 3D prints

Layer Swapping

Layer swapping is one of the most commonly used methods, especially in the MatterHackers office. The design considerations are a lot simpler, but so are the final results. Design your model, pause your print (either manually through your LCD, inserting the pause Mcode into the Gcode you are printing (usually just M600, depending on your firmware), or pausing in your slicer you’re running from), change filament, and continue. We heavily use this method for the MatterHackers Hextile wall since it’s so easy to take a favorite logo or text and make it stand out against the background, and as long as you have different geometry per layer, then the color will come across.

This hextile was paused four different times to get all the colors to come through in the right thickness.

First Layer Inlay

First layer inlay is something that I first heard of from Devin from MakeAnything a little over six months ago. He developed a process of creating 3D models that have a lot of colorful detail on only the first layer, and then swaps filament for the rest. The set up is very similar to the separate piece strategy, except you can’t do complex tops; the inlay will be completely flat.

MakeAnything's Starry Night phone case utilized ten different colors in the first layer.

At home I am building a 3D printer that has a little drawer in the front, and I wanted a custom knob for it. To do so, I designed the basic knob shape in Fusion360, and created a pattern on the front I wanted to have in a different color, and did the same intersection and subtraction technique as before, except this time didn’t do any offsetting to the secondary colored parts, and made sure they were only 0.4mm tall.

The knob in Fusion360 has no clearance, unlike the shift knob.

Once you’re in the slicer, you’re going to import all the parts together, and they should come in aligned to each other. Set the part in the center of the build plate and make sure that you don’t have a brim and your skirt is far enough away to not interfere with the primary colored part. Remove the primary colored part, slice, and start your print (or export to the SD).

The secondary color sliced on its own, ready for printing.

When the print finishes, remove any boogers that could get caught by the primary part, change filament and purge until clean, the Undo the removal of the primary part, and delete the secondary part, slice, and print.

The primary color sliced on its own, without supports so it can melt with the previously printed inlay.

The print should go right over the top of the inlay and melt together cleanly, giving you a super cool two-tone print. Keep in mind that if your printing uses a probing method that requires touching the bed, you may have to either disable it, or instead start these prints in a position that will be clear of the probing routine.

Two layers of red make it just opaque enough to see the shape on the knob

Top Inlay

Top inlay is something I hadn’t considered until a coworker, Mike, showed me it, to which I’ve expanded and created a set of guidelines. Using both first layer inlay and top inlay, you can have a double-sided and flush design - like a double sided keychain. Create a first layer inlay like normal, then on the top surface, instead of extruding into the keychain and calling it finished, add a chamfer or draft angle to the extrusion. This will allow you to print multiple layers of the top inlay, so you can’t see through it (which is possible with one-layer only inlays). The taper is chosen specifically to leave enough room for the taper of the nozzle, making sure it doesn’t crash into previously printed layers. For this method, your procedure will be: first layer inlay, end print, main body, end print, top inlay, end print. Three prints in total to get this effect.

The slight taper to the walls of the letters allow for the nozzle to print in these cavities without fully smearing into the sides.

Each one of these has their place and utility, so don’t be afraid to try one out, find out it doesn’t work for your design, and think about how to incorporate a different method. There may be a point where you need to check out a new dual extrusion printer or a filament splicing method for the more ornate designs, and for that, you can check out MatterHackers.com. I’m Alec from MatterHackers, thanks for reading.

Happy Printing!

How to 3D Print in Multiple Colors with Just One Extruder

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Oftentimes, owning a single-extruder 3D printer feels like you’re missing out on a lot of things. You can’t use HIPS or PVA for support structures, and cannot automatically print multi-colored designs. However, dual-extruder 3D printers can cost quite a bit more.

There still is a way for your 3D prints to have multiple colors – it’s just going to take a bit of extra work. If you don’t mind the extra effort, then check out this guide on how you can 3D print multiple-color models with just a single extruder.

Printing in parts

The simplest way to create a multi-colored print is to separate your 3D model into parts and print these parts separately. This method certainly isn’t for everybody, as you may need advanced 3D modeling skills to pull this off. If you’re just downloading free OBJ files online, you might not even be able to manipulate those freely. Printing in parts is ideal for 3D models that you’ve come up with yourself.

Take note that there will still be limitations to this method. Once all parts have been assembled, you’re going to need to assemble them and glue them together. This may not be possible if your model has odd angles, or if it’s just too complicated.

This may seem like a rudimentary approach to making multicolored 3D prints, but the results are usually good with a bit of creativity and careful planning. If you’re planning to do polishing or post-processing of a multi-part model, it’s best done before assembly.

Use a multicolored filament

Using a multicolored filament is quite an unconventional approach to 3D printing, if only because it lacks any predictability. It involves using a filament that has a spectrum of colors – such as this Rainbow PLA Filament from DO3D.

There are also ways to make your own multicolored filament either by dyeing a white filament or fusing together several filaments of different colors. How much work you want to do is up to you, but there’s always the options of simply buying the multicolored filament.

Printing with multicolored filament results in a model with zones that transition smoothly from one color to another. As we’ve mentioned, this will be an innately unpredictable process. There’s no way to know in which color every single part of the model will be printed.

Instead of treating this unpredictability as a negative, this is actually one of the best things about this method. If you 3D printed the same model ten times using multicolored filament, they will all come out looking different. This element of surprise and variability makes this method novel and unique. You also don’t need any special method or equipment, aside from the multicolored filament itself.

Filament swapping

The most commonly practiced method in the 3D printing community to print in multiple colors with a single extruder is called filament swapping. It involves pausing the print mid-way and swapping one filament for another. It will take a lot of work as you’ll need to actively monitor and step in every now and then during 3D printing.

There are several approaches to this method. You can either do the pausing of the print manually or include the commands in the model’s G-Code. The latter is a lot more convenient but will require that you know how to write and manipulate G-Code commands. The manual method is still viable if you’re willing to do the work.

The number of times that you’ll need to swap another filament will depend on how complex your design is. Although the method may seem simple, it can be very tedious for models that have to be printed in a lot of colors. You can optimize this process by orienting your model in the slicer software such that color transitions occur neatly on layer boundaries. This may not always be possible.

Manual method

To do manual filament swapping, simply pause the print at the point where you want a color change. Manually raise the nozzle using your 3D printer software by about 20 mm. Retract the filament from the extruder and swap in the new filament.

Extrude the new filament, making sure that all traces of the old filament have been removed. Catch the scrap filament with some cardboard you have lying around. You can then lower the nozzle to the original position and resume printing. Repeat this process as many times as necessary.

Semi-automatic method

If you know how to mess around with G-Code, then you can make this method so much easier. Once your slicer software has generated the G-Code for your model, use the layer preview to identify the layers in which you want to do a filament swap. Write these down as you’ll be referring to this list multiple times.

With the layers identified, you can go ahead and look for the layers in the G-Code and insert a pause (M600) command. It would be best to couple this with a Z20 command, which raises the nozzle by 20 mm. Do this for every layer that requires a filament swap. Make sure to run the layer preview again, just to make sure that the G-Code is functioning as expected.

With the G-Code edits in place, your printer should now know to automatically pause when you need to swap in a new filament. The actual swapping step is still manual, of course, but this method is a lot less tedious and prone to error.

Although filament swapping may also seem like a rudimentary method, a lot of 3D printing professionals practice it. It’s the most common method for overcoming the limitations of the number of extruders in a 3D printer – after all, most 3D printers are limited to just one or two. There is a lot of skill needed to pull off filament swapping, but the results are certainly worth the effort.

Filament splicing

Sometimes, splitting up the colors of a model into distinct layers is virtually impossible. Should this be the case, you can augment a single-extruder 3D printer with an accessory with up to four different filaments. This is the idea behind filament splicing – a method that allows for fully automated filament swapping.

The key to this method is the Palette accessory. The Pallete works by accommodating up to four different filament spools. Inside the Palette is a mechanism that cuts, heats, and splices together any combination of two filaments from the selection. This process is very quick and can be automated using the CANVAS hub. The spliced filament is then fed to the 3D printer as a single, uninterrupted strand.

A great thing about Palette is that they have been in the business for quite some time. The latest model, the Palette 2S Pro, is an extremely streamlined product with a host of quality-of-life features. It’s easy to use, requires no calibration, has tool-free maintenance, and comes with intuitive software. It’s also a really good-looking product and its modern minimalist aesthetics should fit quite well in any workstation.

There is a catch, however – the Palette filament splicer is quite expensive. In fact, you can buy a dual-extruder 3D printer for several hundred dollars cheaper than the Palette 2S Pro. This certainly puts into question the wisdom of investing in a Palette accessory.

Other technologies: PolyJet printing

This may already be outside the subject scope of this article but is still worth mentioning because of how interesting the technology is. One of the most advanced ways to 3D print in multiple colors is via the Multi-Color Polyjet method on the Stratasys J750 printer.

The Polyjet method uses photopolymer resin as raw material. This liquid resin is deposited on a build plate through very small droplets and cured by a flash of UV light. What is unique about Multi-Color Polyjet is that it allows the droplets to be colored before deposition. The result is a full-color 3D print with vibrant hues and an excellent level of detail.

Being able to create multi-colored objects using a PolyJet method may just be the peak of multi-colored 3D printing technology. PolyJet is already a superior technology, capable of reproducing highly detailed models using a rapid and reliable method. Combined with a multi-color option, it’s going to be tough for any other 3D printing method to present a compelling alternative.

The biggest downside, as you would expect, is that you can’t just buy a PolyJet printer. This type of printer is ridiculously expensive and typically only used in businesses or corporations. Instead, you can see the output of Multi-Color Polyjet yourself by having a model printed through a third-party service.

Final thoughts

Most people who are curious about 3D printing start with a simple, single-extruder 3D printer. While this is good enough for practicing, printing with a single color only can feel lackluster after some time.

However, you don’t need necessarily need to upgrade to a dual-extruder model just to print multi-colored models. With a bit of creativity (and a lot of tenacity), you can “hack” your way to multi-colored print with just your humble single-extruder printer.

Warning; 3D printers should never be left unattended. They can pose a firesafety hazard.

Multi-color 3D printing with one extruder, in one layer

3D printing

extruder.

As usual, by creating new problems. :)

The material is difficult, not everyone can handle it.

Short video describing the method here:

First, I will talk about the traditional method of multi-color printing with a single extruder, as well as its advantages and disadvantages.

The traditional printing method allows you to create multi-color printouts by replacing plastic of one color with plastic of a different color after printing a certain layer of a part.

i.e. each layer of a different color is stacked on top of the previous layers.

Everyone does it and doesn't seem to complain, it's a quick and easy to implement method to create color prints with a single extruder.

However, the method creates a number of problems (which, of course, I invented myself and rushed to solve it myself :D): Each new color forces us to increase the thickness of the part, creating a relief that is not always necessary.