I got the doorless openings in walls that I was asking about by dragging and dropping door frames into the walls without putting any doors in the frames. It doesn't look exactly like the actual apartment I'm modeling because in the apartment there are no door frames in the openings but it's pretty close.
But, as Hansmex told you, you can get openigs without frames just using the "service hatch" object from the library.
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If a long walk every day were healthy, mailmen would be immortal.
