The idea was to provide with a simple upgrade possibility to many people who have a single extrusion setup. And keeping the cost low and fun high while at it!!

Right now i am designing for a direct-drive setup. But this can be easily modified for a Bowden type extrusion setup.

Also for the cooler, I am using an aluminium block with a heat-sink. (custom design)
but if you wanted to use a E3D v6, simple modifications could be done.

Assumed limitations:
1. filament is wasted trying to avoid contamination.
2. print time is increased because it uses a single hot end.

The setup being designed consists of:
1. Nema 17 stepper, being used for Direct drive extruder.
2. MK8 SS drive. (9mm x 11mm – effective dia 6.8mm)
3. 1 of 624zz bearing each for the two idlers.
4. Some spring or rubber band for tension on the idler arms.
5. Standard size RC servo (~40 gms)

Tips:
1. Calibrate to the lowest temperature you can extrude comfortably.
2. The retraction acceleration value is kept insanely high.(to make sure there are no filament strings in the E3d after retraction)
3. I have tested only with PLA. Maybe ABS works better.