2D Shape Library
While FreeCurve gives you maximum flexibility in creating the from of a Shape, it is often better to use a parametric Shape that is defined by specific logic and controlled by handles that make sense with the logic of the Shape. The Archimatix 2D Shape Library can get you modeling more quickly by providing a rich selection of such parametric Shapes. In fact, much of the smarts of any parametric object in Archimatix is inherent in the parametric Shapes that the object uses.
While some Shapes from the Library are documented here, many others are not. But not to worry–it is usually easy to learn the behavior of any Shape you instantiate from the library simply be experimenting with its handles. You can also author your own parametric Shapes and add them to the Library.