While it is necessary to use CMYK filament in order to use the Crane Quad's color mixing function, it's NOT necessary to use CMYK filament at all times. During the first few calibration prints, as with all printers SOME experimentation is to be expected and you may go through filament while you are getting to know your new printer. We suggest using a filament you are most comfortable with to start. Our test prints have however been sliced with ABS-R in mind.