this got me thinking, if we can get real time feedback for the Z axis, what if we used a laser rangefinder type system to identify how far the print head is from the base of your build area and then by adding small photosensors, one at each corner and one in the middle of your build area, in theory wouldn't we be able to make the Peachy "self calibrating"?

so, the laser would shine and the range finder would count how long the light takes to reach it, then the laser would scan to find the center photosensor establishing that as zero, it would then move to each corner measuring it's travel distance on the X and Y, after locating the corner it would return to center and repeat for the other three corners, it could then take those measurements to determine the X and Y build area and by having the real time Z axis feedback calculating the entire build volume would no longer be required and the machine would be able to calibrate itself prior to each build.

the main reason I am looking into this is I plan to use different sized build resivoirs for different prints ( no need to use a three cubic foot resivoir for a print that only takes up five cubic inches)