I’d like to create a 2D outline from a 3D object. I tried creating a rectangle above the 3D object, grouping it, enter editing, and set view to wireframe and parallel camera so I could see the 3D object through the rectangle. Even though the “tracing rectangle” is between the view/camera and the 3D object, when I create lines/shapes, they’re on the 3D object instead of the 2D rectangle. Any advice on how to do this?
Try giving the rectangle a transparent or nearly transparent texture (low Opacity), and NOT using Xray or wireframe mode. Then the natural inferencing should stay on the rectangular plane. You can check (and force, by holding down Shift) that you are On Face when you click the mouse.
Or use a Section Plane, and the Section Cut Face plugin.