Automatic Cobblestone Generator AND Breaker(Help Needed)

Is there any way to automatically generate cobblestone, and then have a machine and break that cobblestone? I'm building a gigantic castle, and have used all of my cobblestone(~120 stacks) on the foundation and a little but of walls. I also don't want to waste tons of good pickaxes(iron or diamond) or waste time with renewable ones(stone). Is there any bug, or exploit to break blocks of cobblestone?