<p>OK, it just turned up on Thingiverse that someone has demonstrated a trivial machine to do exactly what I asked for: any FDM printer.</p>
<blockquote>
<p>Its sounds crazy, but it works! This technique will allow you to create one offs, and to color match your 3D-prints.</p>
<p>It works by changing the filament (and the color) of your filament while printing, and this causes a multi colored filament, that can be printed again to archive a homogenic-color.</p>
</blockquote>
<p><img src="https://i.sstatic.net/b7aIr.jpg" alt="Rendering of STL file from the link" /></p>
<p>Source <a href="https://www.thingiverse.com/thing:3565827" rel="nofollow noreferrer">3D-Printable Filament! -Print Your Own Filament for Multi-Color!</a>, with <a href="https://www.youtube.com/watch?v=6kbjZobJtbM" rel="nofollow noreferrer">demonstration video</a>.</p>
<p>I'm in the process of trying this and it looks promising! The filament:</p>
<p><img src="https://i.sstatic.net/aT5aP.jpg" alt="printed filament" /></p>
<p>measures 1.65-1.75 mm in diameter and feeds and extrudes cleanly.</p>
<p>The first test print:</p>
<p><img src="https://i.sstatic.net/pICnN.jpg" alt="mixed filament frog next to unmixed comparison prints" /></p>
<p>came out somewhat underextruded, but decent, with uniform mixing of color. Mixed filaments were white flex PLA and blue regular PLA, and the plasticizer seems to have mixed as expected too, but the print feels brittle due to underextrusion still. I suspect with some tuning of flow printing the filament, very good results could be had.</p>
<p>On further inspection, the brittleness/underextrusion seems to be somewhat localized, so it likely comes from <em>inconsistent</em> diameter/density of printed filament. This actually seems consistent with what I saw from the slicer output for printing the filament: there were regions at +/- 45 degrees (+ or - depending on layer) in the spiral where it seems like wall gaps differed and extra gap fill material did or didn't get printed. This could be a slicer bug but it seems more likely it's a bug in the model, and I'd probably do better to recreate it myself in OpenSCAD...</p>

CC BY-SA 4.0
2019-05-02T12:33:15.407Z
This might be not so easy, especially as one of the linsk is a video (although it *can* be done), but could you provide a synopsis of the content of the two links, as if the links die, due to [link-rot](https://en.wikipedia.org/wiki/Link_rot) then the answer won't be as useful as it is currently. Thanks.
Greenonline
CC BY-SA 4.0
2019-05-02T22:10:00.983Z
I thought what I quoted was sufficient to get the idea across. I'll add an image that hopefully does the rest.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2019-05-01T02:46:09.320Z
2019-05-21T15:26:47.487Z
2020-06-18T08:29:41.667Z
R.. GitHub STOP HELPING ICE
<h2>Making your own filament</h2>
<p>Theoretically, this could be done with any filament producing equipment by taking the two filaments and shredding them into pellets and feeding them to the machine in the right mix for the color you want. Industrial setups like a <a href="https://www.filabot.com/" rel="nofollow noreferrer">Filabot</a> are heavy, large and expensive though.</p>
<p>Luckily, hobbyist filament making setups exist. They vary in price and quality but can achieve ok to good results, if you tinker with them a little. Among the kits that I have seen to work is the <a href="https://www.filastruder.com/collections/filastruders-accessories" rel="nofollow noreferrer">Filastruder</a>, but there are also <a href="https://all3dp.com/make-low-cost-filament-extruder/" rel="nofollow noreferrer">DIY instructables</a> that cost less than 200 $.</p>
<h3>Obtaining pellets</h3>
<p>If you are good with mechanics, you might design a feed mechanism that pushes the part filaments with known feed rate into a cutter to pelletize the filament in the wanted amounts to each other, creating a homogenous mix over the length of the filament.</p>
<h3>Blended waste</h3>
<p>As an alternative to self-made pellets to mix in the hopper for the filament maker, one can use shredded waste prints/support structures. After smashing the material to rough chunks, using a blender to gain evenly sized small chunks of 1-2 mm, the stuff should be small enough to feed through the hopper without a problem. the blender also would take care of proper mixing and could take raw filament to mix with <em>used</em> ones.</p>
<h2>Mixing in the hotend</h2>
<p>Mixing filaments in the hotend would need a specialized hotend with two feed ends into the melt zone and two extruders that push the filaments with the same feed rate. The modification of the feeding system would be extensive and demand a custom firmware.</p>
<h2>Splicing filaments</h2>
<p>Another possibility would be a machine that splices the filament in a defined manner. One machine that might be able to do this seems to be the Palette 2 by Mosaic, but it costs (April 2019) round 600 USD. Another possibility could be to use the multi-material upgrade of a Prusa i3 Mk3.</p>
<p>This would generate however a non-homogenous mix of the filaments, the transition zones changing from high concentrations of material A to high concentrations of material B whenever the materials swap. Even with very short areas of spliced material the mix will be inconsistent. With colored filaments, this could generate a rainbow pattern.</p>

CC BY-SA 4.0
2019-04-29T13:10:54.357Z
@R.. could be done with an automatic cutter blade that slices pieces from both filaments as they are fed into the hopper for the feed of the filament making machine. Would need 2 motors running at equal speeds to control feed and a DC one for the chopper.
Trish
CC BY-SA 4.0
2019-04-29T13:16:56.543Z
One feed motor might suffice with good setup of gearing, even allow to adjust ratios based on the teeth of the gear train
Trish
CC BY-SA 4.0
2019-04-29T13:47:18.890Z
Yes, but seems like a lot more gear and places something could go wrong than just mixing in the hotend.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2019-04-29T18:36:17.817Z
@R.. I added my thoughs on both mixing in the hotend via dual-inlet (an idea that was dropped by most makers after how they encountered problems) and splicing. The mixing and making custom filament generates the most homogenous result.
Trish
CC BY-SA 4.0
2019-04-29T20:09:08.967Z
Re: "modification of the feeding system would be extensive and demand a custom firmware", this question is not asking about mixing of filament just-in-time as part of a modified printer, but production of a mixed-color/mixed-material filament in advance, in small quantities, to be fed to an arbitrary unmodified printer.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2019-04-29T20:36:00.110Z
As I told you, the best solution in my opinion is to make the filament from 0 instead of either mixing in the hotend or splicing the filaments. To properly make the filament from 0, you need to pelletize it to get a) a good and homogenous mix and b) guarantee feeding properly.
Trish
CC BY-SA 4.0
2019-04-29T20:38:57.920Z
OK, that's a reasonable answer, but from my perspective it just translates into "what the question is asking for isn't practical". :-(
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2019-04-29T20:41:09.760Z
@R.. it is practical, with some work. another way to make useable pellets is putting waste material (including fresh material) into a blender in the right weight amounts and then shred to a fine mix of evenly 1-2 mm particles, then feed the hopper with that. This would skip the pelettizer.
Trish
CC BY-SA 4.0
2019-04-29T20:48:00.277Z
Indeed, waste material makes it somewhat more interesting, but also dependent on having it present and sorted, and I really don't have much waste. It's still a lot of extra equipment, and not something you'd just prepare on a whim and have ready to use in a matter of minutes like I was hoping for.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2019-04-29T20:52:26.727Z
@R.. Without either a filament splicer or a filament manufacturing setup, yes, it is not something in a matter of minutes.
Trish
CC BY-SA 4.0
2019-04-29T20:54:16.740Z
Do you think my proposals in the question (using a hotend made for 3d printers, with the nozzle modified to 1.75mm output) just won't work? Or that overcoming quality (e.g. consistent diameter) problems would just be too big an obstacle?
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2019-04-29T21:03:50.393Z
@R.. Industrial filament making machines costs 10k ([filabot](https://www.filabot.com/)) and get perfect results. Hobbyist machines like the [Filastruder](https://www.filastruder.com/collections/filastruders-accessories) or [self builds](https://all3dp.com/make-low-cost-filament-extruder/) exist and if you tinker them enough, you get good results too. They have nozzles not the filament diameter and rely on the filament's hang and die-swell to get to the right diameter. You need to feed the arbor with small particles, which means pellets or shredded plastic. You could use *any* plastic though.
Trish
CC BY-SA 4.0
2019-04-29T06:34:59.673Z
2019-04-29T21:15:43.340Z
2020-06-18T08:29:41.667Z
Trish
<p>I've seen questions about (like <a href="https://3dprinting.stackexchange.com/q/2670/11157">What is stopping us from mixing 3d filament colors in an Extruder?</a>) and some solutions for mixing filament colors/materials at print time for multi-color printing, but my question is different: Are there any (affordable) commercially available devices, or DIY/homebrew solutions, for taking 2 or more 1.75&nbsp;mm filaments, mixing them in proportion, and extruding back as 1.75&nbsp;mm filament for use in a printer?</p>

<p>In principle it should just take N extruder drives fed a the right proportional rates, one of the multi-input hotends, a 1.75&nbsp;mm extrusion nozzle, and another drive to pull the extruded filament at the right rate to keep the diameter stable. But I'm curious if anyone's tried and tuned this. Another approach might be taking a hotend made for 3 mm filament, drilling the nozzle orifice out to 1.75 mm, and feeding 3 pieces of 1.75 mm filament into it at once (size seems to match pretty closely).</p>

<p>My interest in this is that I mostly print small things, and it takes months to go through even a single kg of filament, so it's impractical to buy and keep around a bunch of different colors. I'd also like to be able to experiment with mixing flex PLA and plain PLA to get a material with a lot less plasticizer, so that it's not flexible, just less brittle.</p>

<p>Shredding into pellets and measuring out ratios is too much overhead to make it worth it. The key part of the question is doing it direct from filament to filament.</p>

CC BY-SA 4.0
2019-04-29T12:51:16.747Z
My experience (from switching filaments) is that enough mixing takes place in the hotend during printing that even just splicing ~1mm segments would suffice.
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2019-04-30T05:32:37.680Z
that's right. i was more referring to mixing shredded particles (i know it's not  clear in my prev comment)
darth pixel
CC BY-SA 4.0
2019-04-29T09:22:55.037Z
the issue is not as easy as it could seem at first glance. get two and mix them in some proportion... "mix" is the key word and it really hides the main issue. IMO this is the most difficult part of the topic
darth pixel
<extruder><color><filament-production>
Filament mixer?
R.. GitHub STOP HELPING ICE
# Filament mixer?

(Asked by: username_0 on 2019-04-29)

I've seen questions about (like [What is stopping us from mixing 3d filament colors in an Extruder?](https://3dprinting.stackexchange.com/q/2670/11157)) and some solutions for mixing filament colors/materials at print time for multi-color printing, but my question is different: Are there any (affordable) commercially available devices, or DIY/homebrew solutions, for taking 2 or more 1.75 mm filaments, mixing them in proportion, and extruding back as 1.75 mm filament for use in a printer?

In principle it should just take N extruder drives fed a the right proportional rates, one of the multi-input hotends, a 1.75 mm extrusion nozzle, and another drive to pull the extruded filament at the right rate to keep the diameter stable. But I'm curious if anyone's tried and tuned this. Another approach might be taking a hotend made for 3 mm filament, drilling the nozzle orifice out to 1.75 mm, and feeding 3 pieces of 1.75 mm filament into it at once (size seems to match pretty closely).

My interest in this is that I mostly print small things, and it takes months to go through even a single kg of filament, so it's impractical to buy and keep around a bunch of different colors. I'd also like to be able to experiment with mixing flex PLA and plain PLA to get a material with a lot less plasticizer, so that it's not flexible, just less brittle.

Shredding into pellets and measuring out ratios is too much overhead to make it worth it. The key part of the question is doing it direct from filament to filament.

**Tags:** extruder, color, filament-production
> **Comments:**
> **username_1**: the issue is not as easy as it could seem at first glance. get two and mix them in some proportion... "mix" is the key word and it really hides the main issue. IMO this is the most difficult part of the topic  
> **username_0**: My experience (from switching filaments) is that enough mixing takes place in the hotend during printing that even just splicing ~1mm segments would suffice.  
> **username_1**: that's right. i was more referring to mixing shredded particles (i know it's not  clear in my prev comment)  

---

## 2 answers

### Answer by username_0 on 2019-05-01. Score: 2

OK, it just turned up on Thingiverse that someone has demonstrated a trivial machine to do exactly what I asked for: any FDM printer.

> Its sounds crazy, but it works! This technique will allow you to create one offs, and to color match your 3D-prints.
>
> It works by changing the filament (and the color) of your filament while printing, and this causes a multi colored filament, that can be printed again to archive a homogenic-color.

![Rendering of STL file from the link](https://i.sstatic.net/b7aIr.jpg)

Source [3D-Printable Filament! -Print Your Own Filament for Multi-Color!](https://www.thingiverse.com/thing:3565827), with [demonstration video](https://www.youtube.com/watch?v=6kbjZobJtbM).

I'm in the process of trying this and it looks promising! The filament:

![printed filament](https://i.sstatic.net/aT5aP.jpg)

measures 1.65-1.75 mm in diameter and feeds and extrudes cleanly.

The first test print:

![mixed filament frog next to unmixed comparison prints](https://i.sstatic.net/pICnN.jpg)

came out somewhat underextruded, but decent, with uniform mixing of color. Mixed filaments were white flex PLA and blue regular PLA, and the plasticizer seems to have mixed as expected too, but the print feels brittle due to underextrusion still. I suspect with some tuning of flow printing the filament, very good results could be had.

On further inspection, the brittleness/underextrusion seems to be somewhat localized, so it likely comes from *inconsistent* diameter/density of printed filament. This actually seems consistent with what I saw from the slicer output for printing the filament: there were regions at +/- 45 degrees (+ or - depending on layer) in the spiral where it seems like wall gaps differed and extra gap fill material did or didn't get printed. This could be a slicer bug but it seems more likely it's a bug in the model, and I'd probably do better to recreate it myself in OpenSCAD...

> **Comments:**
> **username_2**: This might be not so easy, especially as one of the linsk is a video (although it *can* be done), but could you provide a synopsis of the content of the two links, as if the links die, due to [link-rot](https://en.wikipedia.org/wiki/Link_rot) then the answer won't be as useful as it is currently. Thanks.  
> **username_0**: I thought what I quoted was sufficient to get the idea across. I'll add an image that hopefully does the rest.  

---

### Answer by username_3 on 2019-04-29. Score: 0

## Making your own filament

Theoretically, this could be done with any filament producing equipment by taking the two filaments and shredding them into pellets and feeding them to the machine in the right mix for the color you want. Industrial setups like a [Filabot](https://www.filabot.com/) are heavy, large and expensive though.

Luckily, hobbyist filament making setups exist. They vary in price and quality but can achieve ok to good results, if you tinker with them a little. Among the kits that I have seen to work is the [Filastruder](https://www.filastruder.com/collections/filastruders-accessories), but there are also [DIY instructables](https://all3dp.com/make-low-cost-filament-extruder/) that cost less than 200 $.

### Obtaining pellets

If you are good with mechanics, you might design a feed mechanism that pushes the part filaments with known feed rate into a cutter to pelletize the filament in the wanted amounts to each other, creating a homogenous mix over the length of the filament.

### Blended waste

As an alternative to self-made pellets to mix in the hopper for the filament maker, one can use shredded waste prints/support structures. After smashing the material to rough chunks, using a blender to gain evenly sized small chunks of 1-2 mm, the stuff should be small enough to feed through the hopper without a problem. the blender also would take care of proper mixing and could take raw filament to mix with *used* ones.

## Mixing in the hotend

Mixing filaments in the hotend would need a specialized hotend with two feed ends into the melt zone and two extruders that push the filaments with the same feed rate. The modification of the feeding system would be extensive and demand a custom firmware.

## Splicing filaments

Another possibility would be a machine that splices the filament in a defined manner. One machine that might be able to do this seems to be the Palette 2 by Mosaic, but it costs (April 2019) round 600 USD. Another possibility could be to use the multi-material upgrade of a Prusa i3 Mk3.

This would generate however a non-homogenous mix of the filaments, the transition zones changing from high concentrations of material A to high concentrations of material B whenever the materials swap. Even with very short areas of spliced material the mix will be inconsistent. With colored filaments, this could generate a rainbow pattern.

> **Comments:**
> **username_3**: @R.. could be done with an automatic cutter blade that slices pieces from both filaments as they are fed into the hopper for the feed of the filament making machine. Would need 2 motors running at equal speeds to control feed and a DC one for the chopper.  
> **username_3**: One feed motor might suffice with good setup of gearing, even allow to adjust ratios based on the teeth of the gear train  
> **username_0**: Yes, but seems like a lot more gear and places something could go wrong than just mixing in the hotend.  
> **username_3**: @R.. I added my thoughs on both mixing in the hotend via dual-inlet (an idea that was dropped by most makers after how they encountered problems) and splicing. The mixing and making custom filament generates the most homogenous result.  
> **username_0**: Re: "modification of the feeding system would be extensive and demand a custom firmware", this question is not asking about mixing of filament just-in-time as part of a modified printer, but production of a mixed-color/mixed-material filament in advance, in small quantities, to be fed to an arbitrary unmodified printer.  
> **username_3**: As I told you, the best solution in my opinion is to make the filament from 0 instead of either mixing in the hotend or splicing the filaments. To properly make the filament from 0, you need to pelletize it to get a) a good and homogenous mix and b) guarantee feeding properly.  
> **username_0**: OK, that's a reasonable answer, but from my perspective it just translates into "what the question is asking for isn't practical". :-(  
> **username_3**: @R.. it is practical, with some work. another way to make useable pellets is putting waste material (including fresh material) into a blender in the right weight amounts and then shred to a fine mix of evenly 1-2 mm particles, then feed the hopper with that. This would skip the pelettizer.  
> **username_0**: Indeed, waste material makes it somewhat more interesting, but also dependent on having it present and sorted, and I really don't have much waste. It's still a lot of extra equipment, and not something you'd just prepare on a whim and have ready to use in a matter of minutes like I was hoping for.  
> **username_3**: @R.. Without either a filament splicer or a filament manufacturing setup, yes, it is not something in a matter of minutes.  
> **username_0**: Do you think my proposals in the question (using a hotend made for 3d printers, with the nozzle modified to 1.75mm output) just won't work? Or that overcoming quality (e.g. consistent diameter) problems would just be too big an obstacle?  
> **username_3**: @R.. Industrial filament making machines costs 10k ([filabot](https://www.filabot.com/)) and get perfect results. Hobbyist machines like the [Filastruder](https://www.filastruder.com/collections/filastruders-accessories) or [self builds](https://all3dp.com/make-low-cost-filament-extruder/) exist and if you tinker them enough, you get good results too. They have nozzles not the filament diameter and rely on the filament's hang and die-swell to get to the right diameter. You need to feed the arbor with small particles, which means pellets or shredded plastic. You could use *any* plastic though.  

---

