Make a Color Picker With Your Mix-color 3D Printer!

Have you ever wondered how many colors your mix-color 3D printer can produce? I started with blue, red and yellow and began a color-mixing experiment.

I wanted to start each color combo with a 0%:100% mix and end at 100%:0%. There would be 14 virtual extruders in between, each having a different mix ratio. I wanted to enter this in an Instructables Contest, so I decided to go for it!

While conducting my experiment, I put together some ZIP files that you can download and use to Make a Color Picker With Your Mix-color 3D Printer using Ultimaker Cura open-source slicing software. This instructable will go through the steps to print your color picker using Cura 4.10 on a Windows 10 computer.

• FFF (aka FDM) 3D printer with two extruders and a mixing nozzle
• 3D printer filaments (2 colors)

What Is a Mix-color 3D Printer? It's a 3D printer that can extrude more than one filament at the same time combining them in a single hotend. These printers are popular for producing fancy gradients.

This instructable will demonstrate how a mix-color printer can also output many different blends of colors, making it even more indispensable! If you don't have a dual extrusion 3D printer with a mixing nozzle, then this instructable won't work for you! I use the Geeetech A10M. It has a 2-in-1-out (aka 2-1) hotend like this:

How to Choose Two Filaments: By the end of this instructable you will have made a 3D color picker that you can use whenever you want to print a mixed color. It's easiest to use filaments that have the same properties, rather than mixing different materials. For this reason you might choose two colors having the same specs from the same reliable manufacturer.

You'll get a better assortment of hues at the lighter end of the spectrum! The more opaque filaments don't do as well as the semi-translucents. When I make my next color picker, I won't use the heavily pigmented colors! Look at all of these same reds and blues!

I repeated the steps in this instructable with three different filament combinations: blue/red, red/yellow, and yellow/blue. Depending on your printing production, you might choose to mix green/white or pink/red. What about clear/blue? The possibilities are nearly endless!

Slicer Settings: You should have some experience and knowledge beforehand with respect to the best settings for your 3D printer and materials to achieve a good print. If you don't know your best settings, there are many, many resources and test prints available online to help you get started right away!

Limitation: For me, any interruption in print badly affected my mixing results. In my first attempt, I had tried to print the E1 mix percentage number into each piece, but with printing the number walls and then filling around them, I got "unmixed" results. The partially unblended colors look kind of cool, but, for my color-picker I wanted each piece to be closer to a solid color. I also wanted a printed hole. But, printing with the longest lines possible at slow speed seemed to be the best way to go. I would drill a hole after printing. Turning my models into shapes with no details worked well, but this really restricts what we can make with mixed color.

Patience: Depending on your available RAM, the virtual machine could take awhile to load into Cura. If the is spinning, try waiting.

Time: With the unchanged custom profile loaded, the print is estimated to take 1h 42m. You can certainly change settings to speed this up. Up the printing speed of the primers in Cura's Per Model Settings. Just be sure your extruder can keep up. If your extruder can't output the correct amount of material per prime, you'll get something like this:

Presumed:

• That you know how to download and install software.
• That you know how to extract the contents of a ZIP file to a specific location.
• That your 3D printer is calibrated, leveled and ready to go!

As of July 19, 2021, the so-called "mixing nozzle" doesn't actually mix anything. After reading through several blogs and reports, I learned that, in summary, there are no hotends available on the market which actively mix filaments. Some designs have been thought up and some are in development.

If you have already installed Cura: In Cura, go to Preferences > Configure Cura. Make sure that General > Opening and saving files > Default behavior when opening a project file: is set to Always ask me this or Always open as project. Then, close Cura.

If you haven't already installed Cura: Download and install Ultimaker Cura 4.10. After installation, run the program at least until you see the User Agreement screen, where you can click the Decline and close button. You're not actually declining anything, but this will create some folders and close the program for now so you'll be ready for the next step.

I chose Cura for this instructable because it's open source, in active development and very popular. It's also the only slicer I've tried. Though that says a lot, I dislike the user interface and Cura definitely has some downfalls (especially noticeable in this project) that I hope will be corrected in the future. Firstly, Cura's "prime tower" starts working at layer two. This issue has been handled in the builds by smartavionics. Another inconvenience is that, with more than one extruder, we can't use Cura's Print Sequence - One at a Time mode. And yet another... Although Cura supports up to 16 extruders, the extruders take up almost the full height of the user interface, pushing important model manipulation tools off of the screen! The workaround for this is to install a plugin. The plugin is Sidebar GUI (by fieldOfView). Cura is great and works well for most FDM printers, but its development is focused and prioritized toward the Ultimaker printers. I don't own an Ultimaker printer so I will definitely be trying out other slicers to see how they compare.

Download 16COLORS-cura-defines.zip. Extract the folders (definitions, extruders and materials) to %USERPROFILE%\AppData\Roaming\cura\4.10

Download 16COLORS-cura-project-files.zip. Extract the 3MF files to a location where you'll find them later.

Run Cura and Add a printer. You must have added at least one printer in Cura before you can start using the software. Select 16-COLORS from the Custom category.

The Machine Settings will open. Adjust the settings if needed to fit your printer. If you need to change some G-code, be careful to leave the custom extruders' instructions (M163 and M164) intact.

Step 6.1: In Cura, open the 16-COLORS-COLOR-PICKER.3mf file that you unzipped in Step 4. If given a choice, select Open as project. The 16-COLORS printer with its virtual extruders and materials will be opened in Cura. Make sure that the models are situated on the build plate beyond 10mm in the Y-direction (A nozzle swipe takes the area from Y0-Y10 by default). Since Cura's Prime Tower doesn't start purging until the second layer, the print includes triangle-shaped primers for each part.

Step 6.2: Load a preset profile or adjust the custom 16-COLORS-COLOR-PICKER profile to your preferences. You may want to change the quality, speed, temperatures, infill, retraction, etc. To see all of Cura's available settings, go to Settings > Configure setting visibility... and mark the Check all checkbox.

Required and/or important:

• Layer Start X = 0.0 mm
• Layer Start Y = 0.0 mm
• Nozzle Switch Retraction Distance = 0.0 mm
• Compensate Wall Overlaps = Off (Turn this on if it doesn't badly affect your print)
• Generate Support = Off
• Extruders Share Heater = On

Step 6.3: Slice. Save the G-code. Print.

Since our nozzles do nothing more than heat the filaments, the materials will melt in the nozzle but they won't meld. The final parts consist of four layers, hoping for a result which will look much like a single solid color. Do not fear if your first layer looks funky like this:

What's happening here is that the mixing ratio is correct, but depending on how the mix comes out of the nozzle, we may see one side of it or the other. When you look through a part held up to the light, you'll see it looks like one color. Some printers will do better than others and some filaments do better than others, but without actually mixing the filaments, we can't get perfect results. I've decided that if I want someone to see a single color, my color-mixed prints are best for viewing at a distance, or as a faux stained glass.

Step 6.4: File > Save project... Save your 16-COLORS-COLOR-PICKER.3mf with your modified settings. You'll use it in the future when you make another color picker.

The blue and green materials provide a visual representation of color mixing.

Each part of your color picker is made up of a different filament mix. You'll want to be able to identify each color in some way and specify the filaments utilized. I used paper tags and glue to mark each part with its E1 mix percentage. You could do the same with an opaque marker.

I drilled a hole through my picker parts and put them on a 4-inch ring. Do whatever works for you!

Step 8.1: Use your color picker to choose which colors you want to print with. Then, in Cura, open the 16-COLORS-PRIMERS.3mf file that you unzipped in Step 4. This loads the 16-COLORS printer with the triangle-shaped prime towers into Cura. Delete all the primers that you won't be using. If you're printing with just one mixed color at a time (recommended- saves material), delete all but that one primer. If you're trying to print multiple mixed colors in one print, you'll need to scale the primers to the overlapping heights of objects.

Step 8.2: Open your STL file. In the Object list or on the model itself, right-click to select the virtual extruder matching the E1-E2 mix percentage that you want to use.

Step 8.3: Slice. Print. Done.