Edit Opening Modifier

 
By default, when using the Insert Opening tool, an opening is inserted into a wall by creating a rectangular cutout, even when the block is not rectangular, as in the case of an arched doorway or a circular window.

For non-rectangular openings, you can apply a modifier that will define the shape of the cutout.

1. In the Blocks Palette, select the 3D block whose cutout you want to modify, and click Edit Contents.
   
2. Create the closed, 2D object you want to use as the cutout. Change the workplane if necessary. In this example, a polyline was added to the door face - an exact trace of the doorway shape.
   
3. Activate Edit Opening Modifier. If a modifier was previously defined, it will be highlighted.
4. Select the object to be used as the modifier.
5. Select Finish from the local menu or Inspector Bar.
6. In the Blocks Palette, click Finish Edit Content
   
7. The openings now show the revised cutout shape.

Note: If you want to continue adding more openings, you will have to change the workplane back to Workplane by World.