Liu Xi's ability to cram a bathroom between walls is based on void, not dimensions. It basically translates to the absence of dimension, size, space, etc. That means something of unlimited size can be crammed into a nonexistent space.

Folding is a good analogy for it, since the term is used with void so often. It's like taking a bathroom and folding the exterior of it several times so it fits in between the walls. Entering the bathroom still places you within the physical confines of it, so it looks normal from the inside - same as how the Earth is round, but from a person's view on the ground it looks perfectly flat. Unless Liu Xi folds the interior of the bathroom separately, which she's done to Visionary as a prank. He's probably still recovering.

The limitations are scale, and anchoring. She couldn't fold the Carnifex' tower and hurl it into the space between, because it's just too large for her to handle. Same with hiding the Lair Mansion from some antagonist. Anchoring, of course, means that if she wants to retrieve anything placed in void, or be able to access it from the physical world, she has to attach it to something so it doesn't disappear into oblivion. Liu Xi is fond of using existing doors for that because it's stylish to open a closet and see a whole other place.

While I haven't mentioned specifically, I'm pretty sure there are some failed attempts of hers floating out there in the void, irretrievably.

As for the construction of the bathroom itself: That's just arrangement of elements, which she has slowly begun to perfect.





I would have come up with a far simpler reason: Maybe thud asked for that at some point, and he got a lecture from the worm about throwing off the balance of currency trade.








It's a public University, partly funded by Federal monies, and look, she has an appointment scheduled in the computer every afternoon! Oh, and the golf course has all the tee-times booked every afternoon for a month, and the parking garage managed to lose his car keys.