Interesting problem to solve. I read the intro messages with a different assumption than @droftarts - I assumed you are trying to repair gouges in the PTEX, not dressing the whole base of the ski/snowboard, and my thought was that rather than try to map a gouge, why not have a two step system. Position the "gadget" over the gouge and clamp it to the ski/snowboard. Select one of many pre-defined "patch" shapes. Insert tool #1 in the gadget. Tool 1 is a Dremel tool (or similar and routes a patch to a predefined depth. Then insert tool 2- the PTEX extruder which fills the shape the first tool routed. I can also imagine "custom patch shapes" could be created from a photo of the gouged surface.