This is a early game cobble farm that is stackable just remember to turn the Schematic Cannon settings to Replace Solid With Solid and leave 2 layer in between cobble stone boxes. Add water to the cobblestone stair and two lava buckets in the middle as shown above.

I know this isn't the most efficient farm but it is a very easy early game farm that is stackable that does not cause a lot of lag to servers and low end computers.