This is a design for a dual extruder with a simple magnetic coupling, inspired by OpenCircuitDesign's Makergear M2 twin extruder. Essentially, there are 3 parts to it: a middle block to which the belt is affixed and a left and right block that carry the hotends (E3D v6s). The middle block is spaced so that it cannot attach to both the left and right blocks at once, so through some G-code manipulation it's able to detach and reattach to either block without any extra electronics. This allows for each hotend to be manipulated and compensated for separately similar to dual X carriages, which might be able to eliminate ooze and hotend leveling issues.

Visit this link for OpenCircuitDesign's original article and an explanation of the principles behind it:
http://opencircuitdesign.com/~tim/3d_printer/twin_project/index.html

Project is a work in progress: it's still missing the two parking points on either side of the X rods and no prototype has yet been printed because I'm still awaiting magnets.

I've more or less abandoned this project due to an interest in single-nozzle multi-material 3D printing instead. As it is, it should already work except for the wipers on each end, but is 100% untested and has no G-code written for it yet. This will remain for reference and possibly inspiration, and if I find a month of boredom one day I may come back and finish it.