For this article, I'm moving back into the realm of chemistry software—specifically, the General Atomistic Modelling Graphic Interface, or GAMGI. GAMGI provides a very complete set of tools that allows you to design and visualize fairly complex molecules.
GAMGI has the special ability to make creating repeating structures much easier, which is handy when you're trying to create crystalline structures.
GAMGI should be available in the package repositories of most Linux distributions. For example, on Debian-based distros, you can install GAMGI with the following command: