How to Build a Hidden Piston Door

This is the Jeb door, named after Mojang developer Jens "Jeb" Bergensten, who first used it in a video previewing sticky pistons. The machine is 6 blocks wide, 3 deep and 4 tall. Its bottom pistons have no power of their own: they switch on through quasi-connectivity, a Java-only rule that lets a piston respond to anything that would power the space above it.

What you need

A Sticky Piston is a Piston with a Slimeball on top, and a Piston takes 3 planks, 4 Cobblestone, 1 Iron Ingot and 1 Redstone Dust. Twelve of them cost 12 Slimeballs, 12 Iron Ingots, 48 Cobblestone, 36 planks and 12 Redstone Dust. Each Redstone Repeater adds 3 Stone (smelted, not Cobblestone), 1 Redstone Dust and 2 Redstone Torches, and each torch is 1 Redstone Dust on a Stick. With the 6 dust of wiring, that's 24 Redstone Dust in total.

Slimeballs are usually the bottleneck. Only the smallest slimes drop them, 0 to 2 each before Looting, and a Wandering Trader sometimes sells them for 4 emeralds each, up to 5 times. The slime chunks guide shows where slimes spawn.

Pick door blocks that pistons can push and pull. Obsidian can't be pushed at all, a sticky piston pushes Glazed Terracotta but never pulls it back, and Slime Blocks or Honey Blocks drag neighbouring wall blocks along.

How the door moves

The side pistons, in columns 1 and 6, push toward the doorway. The forward pistons, in columns 2 and 5, face the outside wall with a door block in front of them. Switch the lever on and the side pistons shove each forward piston and its door block into the doorway, under the powered wiring. The forward pistons then push the door blocks into the gap in the front wall.

Lever off runs it in reverse: the forward pistons pull the door blocks back, then the side pistons drag everything into the wall. The repeaters keep that order by holding the side pistons for 0.2 seconds. Pistons can't move an extended piston, so if the side pistons let go first, the door jams.

Build it layer by layer

Each grid is seen from above. The front row is the outside face of the wall; you stand at the back, where the lever goes. The doorway is columns 3 and 4.

Key: S→ and ←S are sticky pistons facing the doorway, S↓ is a sticky piston facing the front, D is a door block, W is a wall block, and a dot is empty space.

A piston faces the opposite way to where you're looking when you place it, up and down included. Stand two blocks away, on the side its face should point to, so you look across at the spot. From the square right next to a bottom-layer spot you look down too steeply, and the piston faces up.

Layers 1 and 2: the pistons

Build this grid twice, the second directly on top of the first.

On each layer, place the side pistons from the doorway (column 3 for the left pair, column 4 for the right), then the forward pistons from the front row, then the door blocks. Build the front wall last, so the front row stays free to stand in. Break and replace any piston that faces the wrong way.

Layer 3: the cap

B is Stone or another conductive block, such as Dirt or Cobblestone. I is the input block: the same kind of block, which gets the lever later. The front row carries the wall over the doorway.

Glass, Glowstone, Ice, Copper Bulbs, Observers and Blocks of Redstone can't be powered, so they won't work. With a Glass cap, the top pistons still fire from the dust above through quasi-connectivity, but the bottom pistons never get a signal, and a Glass input leaves the door dead.

Layer 4: the wiring

1. 1.Put Redstone Dust on columns 3 and 4 of the back row.
2. 2.Place the repeaters (R) in columns 2 and 5, standing in the centre of the back row and facing outward. A repeater's output points away from you.
3. 3.Right-click each repeater once. That raises its delay from 0.1 seconds to 0.2 seconds.
4. 4.Add dust on columns 1 and 6 in the back and middle rows. It links to the repeaters and turns the corner.
5. 5.Attach the Lever to the back face of the input block.

The dust powers the cap blocks under it, and they switch on the top pistons. The forward pistons don't fire where they start: the blocks under the repeaters, just above them, stay unpowered, and the quasi-connectivity reaching them waits for a block update that doesn't come before the side pistons move them. Under columns 3 and 4 they fire on arrival. The bottom layer follows through quasi-connectivity. The redstone basics guide explains how the power travels.

Test it and fix it

Flip the lever on: the door blocks should slide in from both sides, then step forward flush with the wall. Flip it off and they step back, then slide away.

• One side never moves. Its repeater points at the centre. Replace it while facing outward.
• The door jams half-open. The side pistons let go first. Both repeaters must point outward, set to 0.2 seconds.
• Only the top layer moves. Check you're playing Java Edition, and that every cap block under the dust is conductive (Stone, not Glass or Glowstone).
• The door blocks don't come back. One of the pistons is a plain Piston, which never pulls, or a door block is Glazed Terracotta, which sticky pistons can't pull.
• Nothing moves at all. Check that the input block is conductive (Stone, not Glass or Glowstone) and that the lever is on it.

Hiding the door

Use the same block for the door and the front wall, and the closed door disappears into it. Build the front wall one block higher and roof over layer 4 to hide the wiring. All the dust sits on one level, so a roof won't cut the line. The pistons show from the inside, so keep that side within your base.

The lever works from inside only. A button on the input would close the door only for its pulse. With a Redstone Torch inverter (see redstone basics), a button opens it instead, but only for 1.5 seconds with a wooden button. For delay settings, see repeaters explained and the tick calculator.

Next, try the slime block flying machine: sticky pistons taking turns to push and pull, with nothing underneath.