Summary I made this quite a while ago. Thought I would share. The processing script expects two arduinos to be hooked up. One with the arduino sketch I have shared and the other to be loaded with Marlin. The Marlin fork should have some special Mcodes to notify when it's done with certain actions. While I don't think this will be directly useful to anyone, it may help you along Here it is in action Thanks Armatec for your design. It did the trick