Allows to have up to 4 hot-ends for multicolor print.

Demo video: http://youtu.be/NfR9ofFEKFw

The rotation axis is tilted 10° (and hotends -10°) so that only the hotend in use is vertical and touching the bed (all other hotends are then a bit above).
I use it with E3Dv6 hotends, but I think it should work with any J-head hotend as long as the cooling part is not too large.

BOM:

• Thin section bearing: 40mm i.d x 50mm o.d x 6mm wide.
• Nema 14 stepper motor (35x28mm).
• GT2 belt/pulley.
• Micro lever switch for rotation endstop (e.g. 10x20mm).

You can use it with my Marlin firmware (forked from jcrocholl/Marlin):
https://github.com/Edlep/Marlin/tree/feature/rotating_nozzle_platform