Neil’s PP for VCarve is referenced in the community map:
@sweymouth don’t worry about designing in inches and exporting in mm or vice versa, it’s independent and the machine understand both because the PP inserts the appropriate command (G20/G21) to tell it whether the values are inches or mm. I think someone noted earlier that selecting the mm post has the advantage that less precision is lost in rounding errors, because the three digits used in GRBL commands interpreted as fractions of a mm grant a smaller error than three digits interpreted as inches (do I make any sense ?)