If the cats will take a step back he will demonstratively turn on the shower.

The scrungliest one sticks a paw in, then runs a few steps away and shakes off the water.  "The basin."

"Yeah, I can get you a little pool in the park."

"In the cat houses."

"Instead or also?"

"Also is fine if you want."

"If none of you want a pool in the park it would be silly to make one." He adds a water closet situation to the draft cat house.

". . . Will it ever rain here?"

"No."

"Then maybe a cat-sized small rain in the park."

"Okay. I will make a water park section. Do you want a fence between the cat section and the section that will mostly attract human children?"

"Yeah."

He will start a file to design that too.

"There should be places where the - not sunlight but light - streams in."

"Like a window, or like a ceiling window in particular, or like a window with a light outside it?"

"All of those might be nice.  But it shouldn't be light all the time."

"Sure. You can have curtains, if nothing else." Tinker twiddle fiddle.

"What are those?"

"Fabric that goes in front of windows to keep out light and prevent people from seeing into your home."

"Fabric is the thing Twoleg pelts are made of?  Why do you do that?  Should cats too?"

"There is no particular reason for cats to wear them. Twolegs often find it more comfortable and attractive in addition to preferring to not look at some parts of each other's bodies most of the time."

"How could I tell if it's more or less comfortable if I've never tried it?  I don't know about 'attractive' per se but the one Mistoffelees wears looks kinda nice.  And I think Twolegs are nicer to her because of it."

"Do you prefer not to look at the parts of our bodies that her thing covers?" another cat deduces.

"I guess it might help if you were cold but I think having fur probably obviates all the other comfort-related features. And no, actually, the main thing is anuses and genitals which seem hard to cover comfortably on a cat. Twolegs are probably nicer to her because it means a Twoleg is taking care of her, I don't think it's necessarily better than a collar at that."

"I've seen them make different noises at her, though.  And point at her with their paws."