Assemblies are collections of objects that work together to create parametric assets. Assemblies can have any number of mesh objects, curves, and empties, but there is a specific structure that is required for Assemblies. Assemblies all have a base point which is typically a mesh object that is made up of a single vertex. Every object in an assembly is parented to this object. The three other objects that are required are empties that control the X, Y, and Z dimension of the assembly.
Empty Assemblies can be added to the scene from the 'Add' menu found in the 3D viewport header.
There are a number of way to modify assemblies.
The properties menu can be accessed with the right mouse button. This provides access to the assembly dimensions, location and rotation.
Alternatively, a more detailed assembly properties menu can be found in the properties panel (hotkey: N) on the right hand side of the 3D viewport.
The assembly prompts can also be accessed from either of these menus.
Objects can be added to an assembly from the objects tab in the properties panel. By clicking on the '+' button you have the option of adding a mesh, empty, curve or text object to the assembly.
Additional prompts can be added to an assembly from the prompts tab in the properties panel. You can either add a prompt to the currently selected tab in the prompt tabs list or create a new tab in which to add a prompt or series of prompts.