What makes a bathing suit so expensive?

There is a machine in South Brooklyn that looks like a transparent coffin and whirs like an industrial fan. Its metallic innards flit and glide until, within an hour, it releases a swimsuit, dropped from the machine’s underbelly like an egg.

It is a high-tech process that seems simple: Click a button, get a very nearly finished swimsuit. In a way, it mirrors the automated, on-demand, two-day-shipping experience that defines shopping for…