Since last time, I added carbon fiber reinforced rods between the ball joints on the carriages and the ball joints on the extruder platform.
I also added some switches to each X, Y and Z "corner" which will be used to home the extruder. The standard homing procedure which is used, is to quickly move each carriage over the axis up until the switch is closed. It then moves down a few millimeters and moves up slowly until the switch is closed again.
The switch at the top:
You can see the homing procedure, the switch and the carbon fiber rods in this video:
The motor part is here:
The parts are borrowed from RichRap's 3DR printer which in turn is based on the Greg's Wade extruder.
The first half of the hot-end is mounted on the carriage here:
The first print of the printer failed, more on that later. But the printer is working as can be seen in this video: