...So I cut a hole in the wall so that the cats can go from one side of the duplex to the other. It's rough now, I'll fix it up soon.
The cats had been in both sides for extended times, so they knew both places well, but they were carried there in a box. They don't go outside.
Audrey thinks this wormhole is the most amazing thing ever. She runs through the entire place, over and over, one side to the other. The first time she found it the reaction was hilarious - like she just seem the most amazing magic trick ever. She jumped through and looked around on both side several times, like a cartoon double-take.
Iris on the other hand is not amused. She pretty much stays in the front unit.
The hole on this side is wide because (of course) my first attempt hit right dead center at a stud and I had to move over a few inches.