Grbl PCB complete solution with optocouplers

To get rid of the many internal wires inside my grbl /driver switch box i decided to develop a complete solution with an arduino nano and optocouplers like shown on https://github.com/gnea/grbl/wiki/Wiring-Limit-Switches. I want give the OK's a chance because of bad experiences with alarm triggers due electrical static or magnetism from other machines. Also i plan to make a power distribution board to provide the lower voltages for pi, Arduino, display from the 36V source. The project is still in development because i plan to mill the pcb and checking if hand or autoroutig makes more sense to get an mill proof output.