Auto bed level (shown on Solidoodle 3)

###UPDATE: Some bad news!
I do apologize for the lack of updates on this, however a serious of unfortunate events had crippled my progress. During a modification for a better heated platform, I fried 3 transistors, one atmega, one power supply and broke two extruder mounts while I am at. I almost have all parts to get back and going, just need to find some time.
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This is a tentative Thingiverse model until I finalize all parts and populate the gallery with video and more pictures.

###What is it?
Another auto bed level idea that can be adapted to fit your printer,
although I originally did it for my Solidoodle 3.
###Why another auto bed level?
I got tired of performing man leveling of the bed after each print,
and I didn't have any servos lying around, so I wanted to make use
of an opto-switch that I had slavaged off on older printer that I used to have.
###Features:
+ Uses an opto-switch (or opto-endstop)
+ Spring lo