MicroPrint + Slic3r

gcodecomment.sh

#! /bin/sh

for i; do
  #awk '{print;}/move to next layer/{ly=$(NF);gsub("[()]","",ly);print ";LAYER:"ly;}' ${i} > ${i}.new
  awk 'BEGIN{ly=0;}{print;}/^G1 Z/{ly++;print ";LAYER:"ly;}' ${i} > ${i}.new
  if cmp ${i} ${i}.new > /dev/null ; then
    rm ${i}.new
  else
    mv $i ${i}.bak
    mv ${i}.new ${i}
  fi
done