Greetings,
Just curious what most people use to modify their G-code for engraving on non-flat surfaces. Most things i found required GRBL or Mach.
I rewrote some of CNC Gcode Controller since it had Marlin support and its not hard to get to Repteier Firmware from there.
Updated the storage method for the data and added tab file export so its easy to keep the data.
Also set it up to where you can use a Origin point as the zero offset. Next goal is to replicate a surface from the scan of another surface. 
I just installed Marlin on my machine to fix the features setting it up to use Repetier’s probe method in case the default MPCNC group would want to use it with my creature comforts. The original code should work right out of the box for Marlin.
I have gotten pretty good results, but curious if users here already has a much better solution I should try first that i could not find?
*Is it masochistic that I give my PMs the stick to beat us with.
Cheers,
Lucid