You can create masses within a project (in-place masses) or outside a project (loadable mass families). In-place masses are used for mass forms that are unique to a project. Loadable mass families are typically used when you will be placing multiple instances of the mass in a project, or when you will use mass families in multiple projects.
To create in-place masses and loadable mass families, use the conceptual design environment. You can nest other mass families into the mass family that you are creating. (See Conceptual Design Environment.)
If you are importing geometry into a family, see Considerations for Imported Geometry in Mass or Generic Model Families.