How to build the chemical structures?

For any types of simulation, the building of chemical structures is the first important step. Without the structure, nothing is possible.

With the vast of chemical space, the possibility of structures are endless. But luckily, usually we only need to learn how to construct several types of structures (e.g. metal surfaces, oxides, 2D materials, nanoparticles, etc.). But right now we still don’t have a universal builder for chemical structures, which is a pity.