Multi-body parts are used to control complex curves across multiple parts in plastic part design or organic models.
A multi-body part is a central design composed of features contained in bodies that can be exported as individual part files.
You can insert components into a multi-body part file with the Derived Component command. Use the Combine command to perform Boolean operations.
You may find it helpful to review the Guided Tutorial. In Inventor, click the
Get Started tab 
My Home panel
Tutorial Gallery. You can find the Multi-body tutorial in the
Installed Tutorials category.
The tutorial helps you to learn how to:
- Create a complex mounting bracket with three solid bodies.
- Create a work plane midway between two faces.
- Use the Project Geometry command.
- Use the Fillet and Chamfer commands.
- Terminate an extrusion of nthe face of another body to create a complex shape.