Using a single nozzle with three filament feeds like a diamond hotend or a clone it’s possible to create a rainbow of colours with Repetier firmware V0.92.9 mixing nozzle option and RAMPS 1.4 with an extra external extruder driver on AUX1.

Repetier Host can be used with a script with colour names/mix factors or standalone with toolchange (T0-T15) and the weighing factors in the EEprom

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Only the left and right side of the colour tags are not colour identical

The filament goes in on fixed positions in the hotend and actual there is no active mixing in the nozzle, resulting that the print direction influence has on the final colour.

Because the melted filament close to the wall, lesser or not mix with the others for a specific colour mix

The difference is more than only a small colour change, these cubes were printed same time with same mix setting [33%,34%33%], one with the walls parallel to XY and the other 45 degree rotated

The filament extrusion-streams leave the nozzle more or less as striped toothpaste an tube and it is predictable by print direction which filament colour will be dominant on the outside with solid colour filaments.

So translucent filament is now on the wish list as PETG/PLA

Only PETG/PLA needs more cooling then ABS and there is not much space between heatbed and the horizontal X-axis (only 8mm) or between the Mendel90 sturdy smooth rods (50mm)

Modifying the complete x-axis to a vertical orientation like a Prusa printer is a good option and will be the next topics here

The above prints were all with 1.75mm eSun ABS+ (light blue, magenta, yellow).