Since pistons were introduced in patch 1.7, players have been experimenting with their potential uses. Below are some demonstrations and guides. The interest in pistons is their ability to manipulate the position of other blocks.
Traps
Disappearing Floor Trap
When triggered, the section of the floor will be withdrawn from below the target. This design is best used inside to hide the pistons and circuitry. This can easily be added to a tunnel. Under the floor, dig out a 2-block deep pit for each of the trap blocks you want to move. Mine out two blocks horizontally from each space where the trap floor will go and put a sticky piston at the back of each hole. In front of the sticky piston, replace the floor blocks (make sure that the trap block is the same as the regular floor blocks so as not to cause suspicion. In the space beneath the floor can be a long drop, lava, dispensers filled with arrows. For simplicity, we chose lava.
The floor trap when the pistons are activated. Players who activate the pressure plate often have no time to react.
Triggering this is best done with a pressure plate, however, this can be difficult to hide from other players. You will need to wire the pressure plate to the input of a NOT-gate and the pistons to the output. A delay can be helpful to ensure the player is over the right blocks when the trap triggers, which can be accomplished by putting in redstone repeaters. Stone pressure plates will only trigger when players walk over, whereas wooden pressure plates trigger for players and mobs. This trap will be reset once the signal from the pressure plates is disabled.
Alternatively, the pistons could be connected to a lever. This requires input from the player, but can be activated when the target is above the trap, which removes the need for a delay.
Hidden Bridges
Like disappearing floors but in reverse, hidden bridges show an impassible obstacle (usually lava or a long fall) to hinder other players or kill mobs. These bridges can be activated by lever to allow a player to cross then deactivated on the other side or by a set delay.
Suffocation Trap
When a piston moves a block into the same space as the head of a mob or player, the entity takes damage from suffocation. Tunnels work well for this type of trap because the area is small and can hide the parts.
In a tunnel, mine out the ceiling an additional two blocks high. At the top of every part of the tunnel, place a sticky piston then replace the ceiling with the same material used in the tunnel. This trap can be triggered in a number of ways, the most simple being pressure plate or lever. If you choose to use a lever, this trap can also act as a door, since aggressive mobs won't be able to enter. For this example we'll use pressure plate.
Since players are pushed into the nearest air pocket to avoid suffocation, the trigger should be in the middle of a series. To ensure the trap doesn't reset too early, add an RS-NOR latch that is either reset manually or by an automatic delay.
Floodgate
One of the piston's most important uses is it's ability to stop fluids. A floodgate is a device that does just that. Fluids don't destroy pressure plates, which makes them ideal for triggering this trap. In a tunnel, have a pressure plate activate an RS-NOR latch that blocks the player into that tunnel, which will also minimize other damage caused by the fluid. From the same output, have the floodgates open, dropping lava on the target.
Farming
Fence Gate
Gates can be constructed in fences by lowering the target fence, thus allowing the player to walk over. Place a sticky piston below a line of fences. When powered, the fence will be uniform. When unpowered, the fence will be retracted, allowing access.
Reed Farm
A small reed farm using pistons
Reed farms can be enhanced with pistons. Simply align a row of pistons alongside the reeds one block higher than the lowest reed and run a redstone wire round the back. Connect a button to the wire. When activated, the pistons will push the reeds into an illegal position, causing them to turn into the item. The water the reeds need can be used to collect the reed items at the end of the farm. This design does not have a 100% efficiency rate. When the reed is 3 blocks tall or higher, the reeds above the piston level will become items but not be pushed into the stream. This can be fixed with an extra row of pistons, although the material for pistons is arguably more valuable than the renewable reeds.
Wheat Farm
Wheat can be harvested by water that runs into it horizontally (water that runs in vertically destroys the items). Using this property, you can create a floodgate by putting a piston in the way of a source block. Place a lever that toggles the piston so that when the piston extends, the water source is closed up, but when the piston contracts, the water can flow.
Floodgate from Jeb's 1.7 preview
Mushroom Farm
A small mushroom farm using pistons
Similar to the wheat farm, water is used to collect the items. However since mushrooms only grow near other mushrooms you usually want the water only to remove some of the mushrooms. One method to achieve this is to have fixed rows of mushrooms on a raised level which can't be hit by water. After a while, mushrooms will grow in the lower rows which can then get flooded by toggling the piston. The water will push then the mushrooms from the lower rows to their destination point.
Elevators
Single column elevator
Single column elevators made to reach the top quicker are usually short due to their need for complex redstone wiring methods. It can be simplified by using sand or gravel as a floor and pistons to push sand. However, this elevator is much slower.
Stair elevator
This kind of elevator uses a nonlinear design to push the player or an item upstairs. the wiring mechanism is relatively simple while the elevator is fast.
Dry Docks
A dry dock can be made by reversing a floodgate: instead of controlling the liquid, the player is controlling a solid. Place a piston facing upwards in a 1-deep pool of water and wire this piston to a lever. When a boat comes over the piston, flip the lever to raise the boat out of the water. This will stop the boat from being influenced by currents or being bumped.
A dry dock with an water powered launcher feature.
Redstone Circuits
Players have been creating circuitry that uses almost entirely pistons and redstone repeaters. There are three benefits of Piston circuitry:
- Neither repeaters nor pistons 'burn out', unlike redstone torches.
- Piston circuits tend to be smaller than their redstone counterpart
- The resources used are much easier to find and mine.
A clock system using pistons
A 4-phase piston clock
Clocks are a common use for pistons. If two pistons are connected to the opposite sides of a 4-phase clock, each piston has enough time (because of the two unused phases) to retract their plate before the other piston is triggered. This can become necessary for large complicated piston mechanisms.
Locking Chests
A chest with an opaque block above it can not be opened. A sticky piston can be used to replace or remove that block, effectively locking the chest and it's contents. Note that chests themselves can not be moved by pistons. This can be combined with a combination lock for added security.
Light Switches
Pistons can be used to cover and uncover holes with light sources. This can be triggered by a lever or a button on a T-Flip Flop.
Players tend to use glowstone for lighting, however, lava is another viable method. A lava light uses an opaque block to hold the source block of lava from the area it will flow into (generally a glass tube). Since lava can flow, it can be a very space efficient light source. However, lava takes a long time to dissipate. If you need to flip a switch for immediate darkness, flowing lava lamps are not recommended.
Since light levels affect mob spawning, light switches can activate and deactivate a mob farm.
Secret Entrances
Secret Entrances and false dead ends trick players who are unaware of a potentially expansive area. The trick in disguising these is to find a place where the switch is either hidden or thought to do something else.
To make a false dead end dig a tunnel either one or two blocks wide and two blocks high. Remove two blocks above you and two blocks below you. At the bottom and top of the now taller tunnel, place a sticky piston (make sure they face upwards on the floor and downwards on the ceiling) and cover it with stone to make it look like a regular tunnel.
Secret entrance wiring
Secret entrances are more difficult to set up and wire. The design to the right has one set of pistons pull the wall blocks away, and another set to pull those away again. Alternate designs have pistons pulling pistons which requires a good understanding of delay. The recent introduction of pistons means some bugs haven't yet been fixed.
Piston/Piston Secret entrance.
Self Repairing Structures
Self repairing structures use a piston cobblestone generator to endlessly create blocks that get pushed into place by pistons. The following video shows how to create a cobblestone generator, a simple clock and connect it all together to push cobblestone. Self repairing bridge
Self repairing structures are not limited to cobblestone, however, it is by far the easiest material with which to manipulate and the only truly endless supply.
Pistons can only push 12 blocks which limits the scale of the structure. Pistons can not push chests, noteblocks, or furnaces, so these can be used to stop a line of blocks before the 12 block limit is reached.
Mining
It has been theorized that pistons can be used to locate caves through solid rock. In order to do so, one would place the piston on the ground facing the ground, on the ceiling facing the ceiling, or facing straight into any wall. If this cannot be accomplished directly, the piston may be placed, and then all the distance form it to the wall, floor, or ceiling filled in. The piston is then powered. If the piston extends, it indicates an opening within 12 blocks. If it does not extend, then there are at least 12 blocks in that direction. This potentially allows a player to find caves from nothing more than a 2x2 tunnel.
The effectiveness of this technique is limited. Close caves will have sounds (either mobs or ambient sounds) to indicate whether or not a cave is nearby. The limit of 12 blocks can also hinder this method.
Scrolling Display
This will make a columns of blocks move in sync. Make two rows of a movable material (it can only be 13 blocks long because the piston can only move it that far, can be as tall as you want) and make your image/ message built into it. Use pistons to move the blocks across, then back, the across the other way, back to the front/ beginning.
Garbage Disposal
By placing a row of three cobble, then on top of it, a cobble on the left one, and piston (facing right) on the middle one, nothing on the third one and a hole in the ground at the end, one could create a Lava garbage disposal. After following those steps, put a bucketful of lava in the 2 block deep hole at the end, and place a button on the top left block. Unwanted blocks can be 'dropped', using the Q button onto the top middle block, then, after pushing the button the little blocks will be pushed into the lava. CAUTION! This device does not destroy placed blocks, only dropped icons of blocks.
- Lava Disposal(jpeg).jpg
A Diagram of a garbage incinerating device using a piston and lava.