M. To create a polygonal opening in a mesh model

Note: An opening cannot share an external boundary edge. Instead, the external boundary should just be modified to include what would have been the partially enclosed opening edges (i.e., creating a re-entrant corner in the external boundary edge to compensate for the overlapping opening).

In the Parametric Models dialog Mesh Models list, select the leaf called Openings under the mesh model to which you wish to add an opening.
Click Add.
The Select Opening Type dialog opens.
Select the Polygonal Opening option and then click OK.
The drawing will change to display just the mesh region. The right hand side of the screen will display a grid with the grid line settings and spacing.

Tip: The various viewing options and zoom options on top of the screen can be used to obtain a convenient view of the panel.
(Optional) Edit the grid positions using the Snap Node/Panel
Click the points inside the panel to define the corners of the polygonal hole.
Note: The cursor displays a blinking cross (+) at grid intersections. This blinking cross marks the point on the grid at which nodes of the hole boundary may be set. Click points around the mesh boundary in either a clockwise or counter-clockwise order, clicking on the first point a second time to close the loop.
The mesh is regenerated taking into consideration the hole.

Tip: To delete a parametric mesh, opening, density line, or density point, select that entry within the Parametric Models dialog and click Delete.