To add an AC outlet, for example, you just drill a circular hole in the wall, tap into the wiring, add the outlet and you're set. If you don't want it, pull it out and plaster over it with more earth to seal the hole.
I mean it's easier to be in a demonstration if it's a trip that's one of the reasons why the whole thing fell apart in 1971, because it wasn't a trip any longer.

