Anyone V-carving knows that every minuscule difference in lumber height is magnified. Mildly uneven pieces come out correct on one side and hardly touched on the other. (If my math is right, 1/16" difference in height results in 1/8" wider top edge.)

Enter G-Code Ripper by Scorchworks - He's created free software to take height maps and proportionally modify g-code to match. Works with both LinuxCNC and Mach3/Mach4.

Unlike the usual connected touch plate, this needs a resettable probe. Digitizing probes are available on Ebay, but they run $100-300.

This project is an attempt to create a cheap but viable Z probe, and get it to work with Mach3 and Gcode-ripper.