Basic Cobblestone Generator
Are you in dire need of cheap building supplies? Starting out a skyblock island? What if you just want to preserve the natural beauty of your area and not strip mine the land just to build? You will need cobblestone, and this is how to create an infinite amount using only two resources readily found in the game.
For this you will need 1 bucket of water and 1 bucket of lava.
Start by digging a hole 1 block wide and 1 block deep and 5 blocks long. In the very middle, the 3rd block, make it one more block deep. This is to keep the water from overflowing and destroying your lava source! Lava is the rarest block used in this entire tutorial.
In this picture I have used alternating colors (Black and White) wool to show you easier how many blocks something is, and placed glass along the side to give a side view of how it should be.
Once you have that dug out, or built, you can place your water and lava on opposite ends of the hold you have dug. The water will flow up until the 3rd block and stop, and cobble will form right next to the lava. This is because the water is still "touching" the 4th block in, and causing the lava to turn into cobblestone. This is also the reason that we dug the source areas out an extra block, in order to preserve our lava, if you are paranoid and do not want to lose this block you can dig it out up to 2 more spaces out and still have it reach where it needs to reach.
The same principle can be done in reverse for smooth stone (naturally occurring stone) by having the lava flow over the water, but you have to be careful to not lose your lava. This is where a different machine would come in handy, and would make use of redstone.
From here you just mine the cobblestone and it will automatically regenerate! Keep in mind much of the cobble will drop into the lava destroying it, so why not try hooking up pistons to the cobble and moving it away from the lava before you mine it? The basic concept of water flowing into lava will always create cobblestone, so you can add more water from the other direction by flipping the machine and get two spots of cobblestone being made!
My personal favorite is to set up a redstone clock or a BUD switch hooked up to a piston below the cobblestone, then cover the entire machine and have the cobble come out of the ground like a fountain. Another, easier option would be to build above ground like in my pictures and have a piston pushing from behind and sending the cobblestone out the side.
For anyone curious the texture pack used is Sphax.