This is my first post. Don't know if https fotos are visible ??
How can I remove a rectangular area from a wall. My first thought was to create a wall in a wall a make it invisible, but I cannot find how to do that. Maybe other ways to accomplish this ?
Place a service hatch on your wall, reduce its depth and size to match the cutout area you want. Finally make its material invisible in its Material modification dialog box.
Read this tip which explains more or less the same thing.