Flow is a menstrual calendar created through an exploration of the concept of emptiness. The design process was transformative, evolving from early sketches to the selection of techniques that could best embody this idea. Emptiness was interpreted in relation to the cyclical process of menstruation, each month the uterus empties itself, the blood flows out, and a sensation of emptiness remains in the body. This is expressed visually through the persistent presence of red, combined with free drawing and carving technique.