What is the most effective design for an infinite cobblestone generator?

Question

I have one lava and one water. I want to make stone factory, which is:

• the most compact
• the most safe to get stone from it

Answer

I use the design in this post on the Minecraft forums. The design is also shown in this video.

You say you only have one water, but I'm sure it's not too difficult to get another. This generator allows you to mine two blocks, moving your cursor back and forth (so you're not just holding left-click for hours). The water currents will bring the dropped cobblestone towards the block on which you stand. It takes up 5x5x3 blocks of space, and if you build it in a corner of a building, you can omit the leftmost column and top row, diminishing the size to 4x4x3.

To build it, construct the following:

BOTTOM  MIDDLE   TOP  │  KEY
                      │  
█████   █████   █████ │  █ - generator body (solid material)
███.█   ███W█   █████ │  W - water source
███.█   ██.▒.   ██L██ │  L - lava source
█...█   █W▒..   ███.. │  ▒ - cobblestone
████.   ███..   ███.. │  . - empty block
    ↑       
stand
 here

And a video showing it:

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