The Pod

The Pod shortly before Jenny was placed inside it. (COMIC: The Secret Origin of Jenny Everywhere)

According to a partially-unreliable comic book purporting to tell Jenny Everywhere's origin story, the Pod was an experimental dimensional transport created by Jenny's mother and father to allow their daughter to escape the destruction of their universe by the Living Black Hole. Although successful in that, the machine had an unintended side-effect: splintering Jenny across the Multiverse as it literally sent her "everywhere" at once. (COMIC: The Secret Origin of Jenny Everywhere)