A drone photo taken on April 9, 2025 shows an experimental building in Yichang, central China's Hubei Province. An 8-meter-tall and two-story building has completed its main structure in just 22 days during an architectural experiment conducted by a research team from China Three Gorges University. A house-building machine using 3D printing technology was used in the construction of the 100-square-meter experimental building. (Xinhua/Xiao Yijiu)