This is an Arduino Uno + Grbl Shield + Stepper Driver + 60mm fan stack. I have remixed/customized my earlier design for an Arduino Mega 2560 slide-in holder and also the MOAB fan bracket for this setup which can be used to drive a small CNC such as the Shapeoko. The 60mm fan provides the required airflow to run the stepper drivers at or near their maximum current rating (theoretically up to 2.5A for the DRV8825 stepper drivers, but realistically around 2A) without fear of thermal shutdown. The OpenSCAD source code is provided so the thing can be further remixed. License is GPLV3.Here shown printed in Green PLA with 35% infill. Note that the slide-in holder should be mounted vertically so that the Arduino Uno slides in from the top, with the USB connector facing down. The fan brackets require 4 x M3 16mm hex screws and nuts. The slide-in holder is designed for wood screws but can also be used with M5 screws.