Electronic Bed Leveller

This is my first attempt at an electronic bed leveller.
The main Y carriage is from http://www.thingiverse.com/thing:43270 I am using this to test with as i don't have a spare Y carriage.

Using 3 stepper motors attached to the standard reprappro mendel carriage along with a probe attached to the x carrage should allow automatic levelling of the print bed.