Is it possible to mix colours

I am in the early days of using a diamond mixing hot end and have found the slic3r manual to be out of date and does not show the details for the latest stable release 1.2.9.
I can not find anywhere the correct procedure for combining stl files but have managed by trial and error produce a stl file of a vase in 3 colours.
What I am unsure of is if I have done it correctly.

I can not find any way to tell slic3r that I would like, for example, extruder 1 to extrude 35%, extruder 2 to extrude 20% and extruder 3 to extrude 45%.
My ormerod with duet firmware can be set-up to allow mixing with different % for each extruder into one nozzle, so I just need the g-code file to carry the information.

Any thoughts?

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appjaws - Core XYUV Duet Ethernet Duex5
firmware 3.1.1 Web Interface 3.1.1
Ormerod 1-converted to laser engraver, Duet wifi
OpenSCAD version 2020.07
slic3r-1.3.0, Simplify3D 4.1.2, Cura-4.4.1

I use the firmware feature for color mixing. each color is a tool number. you can use something like

M567 P0 E0:0.1:0.2:0.7

to have a color mixing tool 0.

I doubt that there is a color mixing feature in slic3r since you can only attach one tool to a stl model

Yes I know I could set it in firmware but that is not practical if you want to change the mix on the fly or indeed have a different mix for another print.
I suppose this concept is very new and all the development so far has been on single and multiple hot ends, not a single hot end with 3 extruders.

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appjaws - Core XYUV Duet Ethernet Duex5
firmware 3.1.1 Web Interface 3.1.1
Ormerod 1-converted to laser engraver, Duet wifi
OpenSCAD version 2020.07
slic3r-1.3.0, Simplify3D 4.1.2, Cura-4.4.1

Look into Voxelizer. It is a "slicer" that doesn't use STL (though it can if that's what you have). It chops models into voxels - 3D pixels - and each voxel can have properties assigned such as color, material, density, etc. It may be able to do what you want.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Quote
appjaws1
Yes I know I could set it in firmware but that is not practical if you want to change the mix on the fly or indeed have a different mix for another print.
I suppose this concept is very new and all the development so far has been on single and multiple hot ends, not a single hot end with 3 extruders.

You could set up the colour mixes you need for the print in the slicer start gcode. And you can change the colours on the fly using the M569 command as illustrated by DasBasti. You could set up a bunch of macro folders and files to select colours, e.g. create a macro folder called 'Tool 0 colour' and have macro files in that called Red, Yellow, Orange etc. And you can configure as many tools as there might be colours in your print.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

@apjaws1.

I too have recently been playing around with a Diamond hot end. The attached file is a pic of a 7 colour thingy. It was made by defining 7 tools using the mixing feature described above. Using filaments A,B and C the tools are A, B, C then 0.5A+0.5B, 0.5A+0.5C, 0.5B+0.5C and finally 0.34A+0.33B+0.33C. I created a multi layer object in OpenScad and used Slic3R to add parts, giving each one a different tool. However, Slic3R can't cope with more than 4 extruders so I went through the generated G code and, using notepad++ did a "find next" for "T" to find the point where I wanted to change the tool number and edited it. In hind sight (which is always 20:20), a better way of doing it might be to simply create a single part object, slice as normal, then do a "find next" for "Z" to find the position where you want to change the tool and add a new (T(n) command. It's still ab it of a ball ache but not desperately hard to do.

A better way still, might be to simply define a single mixing tool, then change the mix ratio at the required layer height. Of course, all this only works by changing the colour for the entire layer. If you want to change colours for different parts of the same object with might share the same layers, then you are stuck with the number of colours that your slicer can cope with (4 in the case of Slic3R) but they can be any combination of the 3 filaments by using the mixing ratio feature.

Top Tip. If you try to print something with long, non-print moves using standard retraction, you will have ooze and it will come out stringy regardless of how much retraction you use. The reason is that when you retract a single filament, it simply draws filament from the other "inputs" so doesn't create a "vacuum". The solution is to use dc42s latest firmware in which he has kindly implemented firmware retraction and which retracts all 3 filaments by the same amount regardless of mix ratios. You need to set firmware retraction in your config.g with something like M207 S5.0 F2400 and tick the box in slic3r to enable firmware retraction. This will then put the necessary G10 and G11 commands into the gcode file.