What is 3D uterus?

The 3D model of a uterus that Jaehee steals from the women's health clinic is a symbol of her refusal to abide by traditional norms of gender and sexuality. Jaehee steals the model in a fit of rage after the doctor lectures her about her sex life. Stealing a piece of equipment from a doctor's office is, of course, not something a traditional sort of woman would do, just like Jaehee does not conform to what many suppose to be the traditional womanly virtues of chastity and modesty. She returns the model in a show of solidarity with another woman, the nurse from the clinic who also dislikes the old-fashioned doctor.