Saving Custom-Shape Doors or Windows

The shape of the hole is defined by a freely drawn slab or a roof, which is then assigned an ID of Wallhole or Wallniche. Slabs and roofs bearing these IDs will be displayed as a hole or a niche in the wall. (Wallhole and Wallniche are GDL commands used to create holes or niches in walls.)
Go to the Categories and Properties panel and change the ID field to Wallhole if you want to make a hole and Wallniche if you want to make a niche in the wall.
Note: The Wallhole-type element - regardless of its thickness - will always cut through the wall into which it is placed. The Wallniche-type element, however, will cut into the Wall to an extent that depends on its thickness, as set in Slab/Roof Settings. If you are making a Wallniche, be sure to set the element’s thickness to the desired value.
Save the selection using the File > Libraries and Objects > Save Selection as command, and choose Window or Door.
In the Save Door (or Save Window) dialog which appears, enter a name and choose the desired folder location for the new opening:
Click Save.
The Change Object’s Basic Settings dialog box appears. Here, you can define the new library part’s default Surfaces, Fills and Pens.
Note: You can further fine-tune these attributes in Object Settings after you place the library part.
Click OK.