I just consulted Serebii, and it turns out there are two methods of "producing" a shiny. Neither of them really auto dispense a shiny, but it makes the odds a little less insurmountable. First is a method of breeding them. It didn't specify if it had to be a shiny already, but I'm guessing it doesn't have to be. The trick is to "mate" something from two different regions. Such as sinnoh and hoenn.
The next is probably better known. The poke radar can be used to form "chains" these chains can get long if you do it correctly. And after 40 encounters with the same pokemon (the chain breaks if you encounter a different pokemon, or if you fail to defeat the pokemon you meet) there becomes a huge chance of grass not shaking... but GLOWING, that is a DEFINITE sign that there is a shiny. Of course, its a shiny of the pokemon you've been chaining, so you can even tailor your chain to which pokemon you want a shiny of.
This may old news to some, but I felt like tossing it out there. Also if you use the poke radar, don't go for grass that shakes with a yellowish light. You'll be able to tell. Its basically any grass close to you. Use repels to repel the normal pokemon too. And make sure to defeat your enemies, because it ends if you just run away. Good luck!