That's interesting, especially the method they used for designing the actual structure

  > To design the drone, the Northwestern team first used a computational model to generate roughly 20,000 drone configurations capable of stable flight. Then, they used artificial intelligence (AI) and optimization algorithms to repeatedly rearrange the drones’ major components, including a motor, propeller, circuit board, counterweight and batteries. [...] “The design process was fully automated,” Rubenstein said. “Then, when we were confident that a drone met all our criteria, we built it.”

This, I think, is the really interesting part. Not the drone itself