Why do scientists  build 3-D molecule to understand certain medicine?

In our global health Cure class, we built our own 3-D molecule of different types of medicine. My molecule is Zidovudine. This medicine treats HIV. Zidovudine,  slows HIV spread significantly, but may not always stop it entirely. Zidovudine  was a major breakthrough in AIDS therapy in the 1990s that significantly altered the course of the illness. It helped destroy the notion that HIV/AIDS was a death sentence. (2012 – HealthcareMagic)

Building my molecule was such an interesting experience for me. It was really challenging to build. We used styrofoam  balls and wooden sticks to build our molecule. Each ball was a different color. For example, the red balls represented oxygen, white are hydrogen, blue  were nitrogen, and gray represents carbon.