https://phys.org/news/2018-08-d-colloidal-crystals.html

"If you blew up each particle to the size of a soccer ball, it would be like stacking a whole lot of soccer balls to make something as tall as a skyscraper," says study co-author Alvin Tan, a graduate student in MIT's Department of Materials Science and Engineering. "That's what we're doing at the nanoscale."

The researchers found a way to print colloids such as polymer nanoparticles in highly ordered arrangements, similar to the atomic structures in crystals. They printed various structures, such as tiny towers and helices, that interact with light in specific ways depending on the size of the individual particles within each structure.