Single and dual extruder FDM printers are commonly available these days but machines with support for 3 or more hotends are still hard to find. The current approach to dual/multi extrusion is either a XY carriage moving multiple hotends or a single hotend with several filaments feeding into it (eg. E3D Cyclops, Diamond Hotend, Prusa i3 MK2 Multi Material).
Both designs have their own limitations with regard to scaleability. For the first it is size and weight of the carriage, the second requires all materials to be within a similar temperature range.
This design overcomes some of these limitations and requires only off the shelf components (pins, bushings, magnets), 3D printed parts and most importantly no additional motors, servos or other electrical components. Modification of most CoreXY/H-Bot style printers should be possible
|Tool head making a contact with on of the extruders|