VertX

More on the wiki : http://reprap.org/wiki/X-carriage-struder

That's my vertical x-axis idea of a compact extruder integrated into the x-carriage, thanks to direct drive and linear bearings.

It was designed for the "classic" Sells Mendel, as a sort of upgrade, but it's also compatible with the Prusa Mendel (same spacing between z-rods).

The carriage-extruder is compatible with most of the existing hotends, or just ask for a diameter if your thermal break part (ptfe/peek) don't fit my 13m