You can create a new part in the context of an assembly. That way you
can use the geometry of other assembly components while designing the part.
You can also create a new subassembly in the context of another
assembly. See Inserting a New Subassembly.
Before you begin:
Specify the default behavior for saving new in-context components.
You can save them as separate external part files or as virtual components within
the assembly file. See
Saving New In-Context Components.
To create a part within an assembly: