I have seen a probe that you place in the spindle head or router that turns the cnc into a scanner is this working ok
do you program mach3 to scan and do the probe results go straight to the computer , the become an *.stl  file how does all this come togther

Look at the download section in this forum and download the << Digitizing / Probing>>  plug in

I think you can program the X and Y step for the probe to take measurement and it store the file in X , Y and Z point. I think you can read it with wordpad because it is in text format.

Hope this help, never tried it.

Jeff