everybody is asking the same question so read it here please :

---- there is no software support for this thing yet. ----

i made it work without issues in klipper using "manual_stepper" , and the " Filament Sensor Module" with shitloads of crappy macros.

wont publish any of that. the day i have a working extra module (its called now MMFF , Massive Multi Filament Feeder) i will publish it. somehow.

if u wanna do it for yourself and publish it before me i will be truly glad. im not a jealous guy. be free, share, be happy, get a beer, kiss your beloveds. cheers.

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Edit7 : uploaded step and iges files. not tested. may be a mess. becouse u know, autodesk destroyed fusion360 so we dont have no more download links

Edit6 : https://a360.co/2AkcbUj

A better filament sensor , and here, lo and behold!!! some trash dirt BOM


structure

5 5mm (yeah, proper metric stuff) threaded rods, the length u like
10 5mm nuts
1 4mm trheaded rod
1 5mm diameter hardened steel rod (for the mk8 , u will have to flatten a bit of it )
1 8mm hardened steel rod
1 8mm threaded rod AND NUT (get a fast one, u dont need precision really 12-14mm lead)
2x nema 17 servos. ( there are servos with long 5mm rods and with integrated 8mm threaded rods , it will be very nice to use them!! but i dont have em')
2x micro switches, one for the endstop another for the carriage
1x 5x5x5mm neodimium magnet
1x 10mm diameter steel washer STEEL , NOT STAINLESS STEEL
1x mg90 servo

each port needs

1x 1/8 bsp pneumatic fitting
1x 3x10mm screw (hex)
1x MR85-ZZ 5x8x2.5mm bearing
1x 623zz 3x10x4 bearing
1x hand made spring, with love
1x mk8 11mm long hobbed gear

motor plate

1x 625zz
1x f688zz ( one of the threaded rod ends, the one that faces the motor
1x kfl08
2x 5x10 mm screws
2x 5mm nuts

15x 3x45mm hex screw
4x 3mm hex nut

carriage

3x 3x25 hex screw
6x 3x15 hex screw
6x 3x25 hex screw
15 3mm nuts
1x 1/8 bsp pneumatic fitting

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Edit5 : mechanically sound and working as i need it now.
3d model and download link
no code yet.

whole thing video, 11 ports
cute cablechain video

       check on the litle springs on every lever. they are needed to use this contraption at       any angle. really a pain in the ass to build. destroyed my fingers. literally have them       with multiple bleeding holes.      as always, be aware.. there may be dragons. 

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Edit4 : the never ending upgrading https://a360.co/2ROlq2O

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Edit3 : latest and i hope final. https://a360.co/2OlJcW5

software time..

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Edit2 : New version incoming...

view in 3d : (damn you thingi, no iframes? ) https://a360.co/2IH8S9O

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Edit 1 : inverted gears version. so the direct extruder does almost no extra work

so you need to print large stuff and cant access large filament spools?

say no more.

work in progress. have not the time or the spare filament to test-print this stuff yet

donations welcomed :)

on electronics part of the thing, the idea is to use 2 extra extruders of your 6 drivers board and some endstop who is embeded on the carriage. cheap. no extra electronic stuff.

close to no supports needed while printing the parts.

another idea is to make it stackable. so you can add as many extra filament spools as you want if u have large enough 5mm shafts / screws.

yeah it looks like the new prusa multi material but its just a common problem with a common solution.

it may work as a bowden extruder but i dont plan to use it like that.

the working idea is that when the carriage moves it enables the extruder to feed the material on that port.
first port may be a utility port. to eject leftover material. or not.
when u sense that u dont have more filament left, u move the carriage to the first port and retract with your main extruder. then u pick whats left of the filament on the ptfe tube with the hobbed bolt on the base who need to be runing backwards and eject all the filament... lets say u sense the filament runing out again on the carriage, then retract a bit more.. so you are sure there is nothing left.
now you can procede to load a new filament that needs to be in some other input port.

you can print and add as many ports as u like or desire.

it may work as a a prusa multi material retarded brother who lives in the ceiling but i still dont know exactly how. i think u will need to use a filament input port with a steel flexible wire to purge the extruder, and an ejection port if u plan to use ptfe tubes from the spool holders to feed filament to this thing.

its a work in progress...

you can view and download the model on https://a360.co/2IbFnyX

inverted gears version : https://a360.co/2JqCafO