Click here to find out how engineers do it.
Writers would build a cat by making dozens of prototypes, many of which involve minute changes and/or allowing the prototype to sit in the corner until it decided it was ready to be used. In the meantime, they’d talk to it and expect it to talk back to them. Everyone else on earth would be confused by why a creator would talk to his or her creation or how on earth such a thing was even physically possible. Authors wouldn’t, though. We’re used to that sort of magic. 😉
How would you profession build a cat?