These two small parts (cap and mount) can be used to convert your da vinci 2.0 duo to a single extruder E3d V6 without having to print an entirely carriage.

The cap does not need supports and I chose to print the mount with supports to minimize clean up. I also removed the second stepper motor on the carriage which has reduced weight significantly and has allowed me to print at 80mm/s without resonance in the x or y direction.

In Repetier EEPROM setting, I changed the lowered max z-axis by the difference in height between the original and the new nozzle. There is an optical end-stop sensor for the z-axis which is used to home the z-axis. there is a piece of metal on the bed which trips the end stop. I glued a piece of paper on to this, metal tab, to effectively extend the tab the distance of the which you changed the max z-axis travel. Sorry I don't have any pictures of this at the moment, I'm away from home for the next two weeks. You'll have to poke around your printer settings and take a look at the end stop to figure out what I mean.

also there is a small support in the bottom of the carriage which needs to be cut off to allow room for the cold end fan. The fan is 12v so I chose to run a line from the PSU which is turned on with the printer.

required materials:
about 10m of T-glase or ABS
2x m6x16mm (maybe 20mm?)
2x m6 nuts or nutserts

Version 2 of the mount is untested but should add extra stability to hot end although I haven't seen any need for it. If you test it, please let me know.

I have plans to convert to bowden to decrease weight further. Will update once I find the time.