Mirrors

>Own fluffy pony
>Get two mirrors
>Set them up analog to each other
>Plop fluffy pony down in between them
>Fluffy pony awes at the endless corridor illusion
>It instantly gasps about, "new friends"
>Fluffy pony jumps into the mirror nearest it
>Fluffy pony enters the mirror world, and another fluffy pony enters yours
>This goes on for a while
>You remove one of the mirrors from the equation
>The fluffy pony currently inhabiting your world crashes into the next mirror and breaks it
>"Ow!! ...Crikey, what's this trick?!" it mewls in a thick Australian accent
>Fluffy ponies are apparently capable of inter-dimensional travel via mirror
>Nobel prize!