Chris have suggested his Sharpie Dotifier robotic arm that can draw pictures by doting a pen.
He didn’t use any fancy stuff that would make it similar to CNC, but used one stepper motor and five servo motors to form robotic arm allowing to move, down and grip object. Just give it a pen and ti starts drawing in a manner of dot matrix printer. Servo motors are driven by PIC18F452 microcontroller whicl also sends signals to stepper motor controller board which is build around L298 controller. Stepper motor slides arm left and right, so arm could cover whole paper sheet. PIC microcontroller accepts commands from laptop computer equipped with serial port. PC application simply reads bitmap image and sends data where dots has to be put. Great work- just keep those pictures coming.