An essential Fallout 4 mod.
Snap'n Build is an extremely useful settlement building tool. When enabled, you'll see a new Snap'n Build tab under the Structures tab in the Workshop.
Once you're in there, you'll gain access to easy-to-build structures. Examples include a Greenhouse, a bunker, brick houses, and more. There's also an in-game configuration menu that makes it extremely easy to navigate.
So if you want to add some additional structures to your settlement and you don't want to spend a mind-boggling time doing so, take a look at this mod.