DIY Multicolor Fused Filaments: Review & New Technique




Introduction: DIY Multicolor Fused Filaments: Review & New Technique

I recently started experimenting with multicolor 3D printing. But as I have a single extruder 3D printer, the task is a bit more difficult than with multiple extruders... So below are my tips to make multicolor filaments easily.

Why multicolor printing?

  • First, to make aesthetic objects.
  • Second, because it can be a nice way to recycle scraps plastic that broke from the spool, or from a finished spool.

How to do?

  • I have made here a review of the best technics I found on the internet, with the pros and cons of each one. So you are free to choose your favorite method. See step 1.
  • And I also explain the one I use. Which is the simplest method, and it requires almost no material. See steps 2 to 6.

Before to start:

Making multicolor filament is fun and it can give great results. But keep in mind that sometimes painting your printed object gives better results! Also, I present here 10 technics found on the internet and the one I am using (so 11 different methods). To my point of view, mine is the easiest and simplest method to use, but it has been many months since I am using it, so I have practiced a lot. You are free to experiment each method to find your favorite.

Step 1: Review

Here are my favorite references to print multicolor objects with a simple extruder.

By changing the filament during the process:

  • Manually pause the printer. Here there is no need for references I guess. Just stay close to your printer, then once you want to change the filament, hit pause and change it.
    • Pros: Choose when to stop the printer.
    • Cons: Stay close to the printer when printing.
  • Automatically pause the printer. Just add a line in the gcode file to pause the printer. Here are two references using this technique, in step 4 here [ 1 ] and also in this instructable [ 2 ].
    • Pros: No need to stay close to the printer.
    • Cons: The printer will not finish the object until you change the filament and press continue.

By making multicolor filaments:

  • Using Sharpie markers. I guess it is one of the easiest technics to make multicolor prints. It is explained in details here [3]. And here is an instructable dealing with this technics and 2 markers at the same time [4].
    • Pros: Cheap and simple.
    • Cons: The colors are attenuated.
  • With a hair straightener. I have seen this technique in this instructable [5].
    • Pros: Quick and easy.
    • Cons: Need a hair straightener.
  • Using a homemade fuser [6].
    • Pros: Quick and easy to fuse.
    • Cons: Components to essemble (3D printed parts and electronic).
  • With heat-shrink tubing [7].
    • Pros: Cheap.
    • Cons: Temperature sensor not easy to place.
  • With a 3D pen [8].
    • Pros: Simple.
    • Cons: Need a 3D pen.
  • With a soldering iron [9].
    • Pros: Simple device.
    • Cons: Might damage the iron.
  • With another homemade device [10].
    • Pros: Neat fuse.
    • Cons: Pieces to assemble.
  • Or aluminum foil [11].
    • Pros: Simple.
    • Cons: Filaments might bend.
  • And finally, using a lighter or a candle. [see next steps]


Step 2: Filament Fusing

In the next steps, I'll explain how I am fusing filaments to make multicolor prints. This works with PLA, I never tried with another plastic. The process involves fire, so make sure you're doing it in a safe area. I am not responsible in case of a problem.

Here is the material required:

  • A lighter/a candle
  • Cutting pliers
  • A file
  • Eventually, the same heat break used on your 3D printer

The first step consists of burning the tips of 2 filaments (place them in the flame, and blow on it when they are burning), and to firmly press them against each other. If you do not press firmly, they will bend and it is impossible to fuse them. Then wait many seconds (up to 30 seconds) and try to keep the filaments aligned. When you think they are aligned correctly you can also blow on the fused part to cool it down.

Step 3: Rough Smoothing

After the fusion between the filaments, a disk of plastic is formed where the filaments have been burnt. With cutting pliers you can remove most of this plastic disk. This will help a lot for the next step.

Step 4: Advanced Smoothing

Now with a file, it is possible to sand the merged filaments so the fused part is as smooth as possible.

I have also used a Dremel with a sanding bit, and it is really efficient.

This part is the most difficult, but it is also really important because the filaments can get stuck in the hotend if not sanded correctly. Actually, it also applies to most of the other technics reviewed previously even if the authors do not explain it. I'd rather use fused filaments slightly thinner than the regular filaments, to avoid blocking the hotend and the nozzle of my printer.

Step 5: Test Before Printing

Before placing this filament inside the printer, it is better to test if it the filament is thin enough. To do so, I have used a heat break and moved the filament through it. If it gets stuck, you have to sand again.

Step 6: Have Fun!

Here are some examples of multicolor prints I have made. I am using an MP Select Mini 3D (V1), and I never had any problem with this method.

If you have a favorite method to make fused filament please share it in the comments!

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    Tip 4 years ago

    I want to clarify Antzy's tip which is not correct: with my method, there is no risk to cause a clog in the hotend, and below I explain why.

    As Antzy Carmasaic said, burning a PLA filament on an open flame introduces soot particles, and this can clog the hotend. BUT with my method, when the filaments are fused together (step 2), the soot particles are expelled on the edges of the fused parts when the filaments are pressed firmly. And these particles are removed when during sanding.

    As a proof, check the photos below. I have added one with soot particles after it has been burnt in a flame. Then another one after the fusion, and we can clearly see the soot particles on the edges. And finally a photo after sanding, and we can clearly see that the fusion is quite clean!

    Finally, I have used this technique a lot and I never had any problem. And if someone clog the hotend with this technic, I'd rather say that it comes from a bad sanding and that the filament is too large to pass through the hotend, than because there are soot particles.

    I hope it clears things! :) Don't hesitate to give it a try to verify, and if you think it can damage your printer, of course, don't take the risk.

    Antzy Carmasaic
    Antzy Carmasaic

    Tip 4 years ago

    Your method of fine for a quick and dirty join. But burning filament on an open flame will introduce soot particles in the joint and the PLAs will be degraded to the maximum limit. That can cause a clog in the hotend, especially if there is already a partial clog in there.
    I would preferably use your method with a hot air gun to only heat and not burn the filament without direct flame contact.


    4 years ago

    I will have to try this when my printer is fixed lol. Thanks!!!


    Reply 4 years ago

    Sure, you can make some great prints with fused filaments!

    What problems do you have with your printer?


    Reply 4 years ago

    My 3D printer broke and while it is broken I am spending my time upgrading it lol. Thanks!!!


    4 years ago

    Nice instructable! Definitely will use. I have struggled before with changing the filaments so I think fusing is the best way to go for me. Thanks for sharing


    Reply 4 years ago