Auto Z Stop with Lower X Axis for Prusa Mendel i2

This is work in progress
Up Date: 2018
The Floating z Axis is preforming very well, the micro switch option works with marlin's
auto level feature, using the hot end as the probe.
I have not done any more on the tool holder.

Update 2018:
Here is a link to my 3d Printed Printer: that has the floating "Z" the project has worked beyond my expectations. https://www.instructables.com/id/Long-Bed-Printed-3d-Printer/

Up Date: 2014
I added a Micro Switch to the lower "X" Axis. nuts and bolts on
each side of the switch can be used to set the height to trigger
the micro switch. This switch is wired (n/o) when in contact with
"X" carriage this will close, completing the "Z" circuit.

I have been designing a Lower X Axis for tools/accessories to be
used during the printing process. By putting the Extruder/Hot end
in a standby mode. Then have the X carriage connect to one of
the tools/accessories on the lower X axis, then do it's work.
Park the tool/accessory and continue printing.

After seeing Radus's "Auto Touch Z-End Stop" for the Prusa i3,
I believe this could be an option for an
Auto Z end stop / Bed Leveling System
for the Prusa i2.

The Rods for the Lower X Axis do Not need to be installed to
use the Z auto stop function.
There is also a file with the lower X rod clamps removed.

This does not reduce printing area.