User:MentalMouse42/Sandbox/Farm Design

Pumpkin/Melon Farm Design 4
The following stackable design sacrifices space efficiency in order to fully automate harvesting. The total area of the farm is 13 blocks by 7 blocks, with alternating piston and farm layers. Farmland is hydrated by water flowing down from above. A pressure plate at the end of the collection area on the bottom activates a redstone torch tower, which in turn activates each piston layer. Melons fall down the empty middle area into flowing water at the bottom layer. Notes:
 * To speed up collection, place ice blocks under the watercourse.
 * The farm can be lit from within by glowstone as shown, or jack-o-lanterns. If using jack-o-lanterns for lighting, temporarily put dirt blocks in place of the pistons, put jack-o-lanterns on top, and then replace the dirt blocks with pistons.
 * The pressure plate can be replaced with a hopper or two, leading to a chest or two south of it. Then the redstone can be triggered with a switch anywhere along its length.  However, a sufficently tall farm may produce enough goods to overwhelm the hopper.  (750 items -- call it a dozen stacks -- will take 5 minutes to absorb, so additional stacks may expire.  Twenty or so levels of melons could do that, or most of a hundred levels of pumpkins.)

To build the farm:
 * Start with the base layer: The farmland squares should be planted with your seeds, while the dirt is where pumpkins or melons will grow.
 * Then, alternate piston and farm layers, as many as you want. This is the stackable section, you are limited only by resources.
 * After the last piston layer, build the cap layer instead of another farm layer. The black wool indicates temporary blocks (any solid, non-falling, block will do) which you will remove after placing the water on the top level.
 * Last of all, build the top layer, place the water, and mine out those temporary blocks. For the top-most layer, all the water blocks are sources.  The Art of the Bucket will assist in filling them quickly.  (In each row, place the first and third source blocks, then refill your buckets from behind the last block you placed, to add the fifth, seventh, and eighth.)

Schematics:

This design is based on the following video: