How do I perform 'shiny swapping'?

In Pokémon Sun and Moon it's possible to 'shiny swap' Pokémon as a method to gain shinies. How does this method work? I'd love to get some legal shiny Pokémon, but I don't get how the shiny swapping method works. I'd be very interested in knowing how to do this and if there are any caveats to it.

1 Answer

_{(I have found this on Reddit weeks ago, but I don't remember where exactly, so I don't know who made it.)}