OiMy — Anatomy

A message is a marble dropped at the hopper. It rolls down one conveyor, through real machines wired to do one job each: a turnstile, a bank of lockers (one per family), a switchboard that routes the call, a stamping press or a work-cell that handles it, and a vault at the end. Press the send button on the hopper to fire it yourself, or let it run. Throw the big switch to swap the whole engine — the machines it bypasses just go dark, they don't vanish.