The Laser Piston

Functionality

• Pistons will be facing the Player when placed.
• Pistons are redstone triggered. When powered, their wooden surface extends outwards by 1 block, pushing up to a maximum of 12 blocks.
• Similarly, if a block pushed by a piston is pushed into a player/mob, the player/mob will get pushed if there is space. If there is no space, the block will start to occupy the same space as the player/mob and cause suffocation if the block is opaque.
• When blocks are pushed by a piston, they are momentarily non-solid and cause any players/items on the moving block to fall through the moving block.
• Pistons can be used to toggle fluid flows like a flood gate by extending into or retracting from the space where the fluid would flow through.
• Pistons can push Minecarts and Boats. Note that if the minecart is on a rail, the rail will also get pushed, making it a drop.
• Pistons are usually used to create doors or traps such as massive opening pits.
• Adding a Slimeball to a Piston on a Crafting Table creates a Sticky Piston .
• If a piston pushes a Slime Block which has any movable blocks attached to it, than the Blocks will move as well. This method won't push un-movable blocks. You can create "flying machines" with this function. A piston with a Slime Block can only push up to 12 blocks.
• This method won't push un-movable blocks.
• You can create "flying machines" with this function.
• A piston with a Slime Block can only push up to 12 blocks.

Blocks

• Some blocks cannot be pushed by Pistons and the piston head will not extend: Obsidian , Bedrock , Furnaces , Chests , etc.
• Pistons will not push blocks into The Void or the top of the map.
• Pumpkins , Cobwebs , Dragon Egg and Jack-O-Lanterns are turned back into items when pushed. (If trying to create extendable/retractable lighting, one can use Glowstone instead.)
• Melons will turn into slices if pushed by a piston.
• Pistons cannot push water or lava , only obstruct it. A piston head extending into a water or lava source block will destroy the source block.
• Pistons cannot push most blocks that are "attached to a block” such as levers , torches , redstone , signs , etc. They will be detached and drop as an item. Exceptions include: Trapdoors , as long as their hinged side remains attached to a solid block in their new position; Rails (and Powered Rail , Detector Rail , Activator Rail ) as long as they remain on top of a solid block in their new position. Rails will re-orient themselves after being pushed just as they do when placed manually.
• Trapdoors , as long as their hinged side remains attached to a solid block in their new position;
• Rails (and Powered Rail , Detector Rail , Activator Rail ) as long as they remain on top of a solid block in their new position. Rails will re-orient themselves after being pushed just as they do when placed manually.
• Blocks that are attached to pushed blocks will be broken off unless the block which is now under/behind them is also acceptable; for example, torches can be placed on a "self-repairing" cobblestone structure.
• Pistons cannot push a chain of blocks more than 12 blocks long, or else they will not extend.
• If a block that is extended by a piston upwards by one and it does not obey physics, it will float in mid-air when the piston is retracted.
• Pistons Corrupt in the Far Lands .

Trivia

• If a piston pushes a gravity-affected block over a hole, the block will fall, even if attached to a sticky piston.
• Pistons cannot be used to 'crush' players or mobs against walls. A piston will simply pass through them if this is attempted. However, blocks being pushed by piston will crush players and mobs and suffocate them, making it useful for traps , and pistons can be used to make pits appear/disappear and start/stop flows of liquids, which can also help with traps.
• Pistons were first introduced in the "Piston Mod", then they were implemented in the game officially.
• In beta 1.7.1 there was a block duplicating glitch using pistons and sticky pistons.

See also

• Sticky Piston