Minecraft: How to Make a TNT Duper

Minecraft players have always been annoyed by the significant material cost of TNT. Still, players have found a method of duplication that Mojang states is a permanent feature for Java Edition. This duplication method is far cheaper than just firing TNT rapidly out of a dispenser and can be incredibly useful for a wide array of Redstone contraptions.

This TNT Duper is relatively inexpensive but will take a Coral Fan, which requires Silk Touch to acquire. This duplication has many designs, but Minecraft players have settled into a primarily standardized way of doing it. Regardless of the method, the contraption will take:

1 Sticky Piston
(At least) 6 Slime Blocks
(At least) 1 TNT
1 Fence or Wall
1 Coral Fan
1 Detector Rail
1 Minecart
Some method of activation, like a lever.

How to Build the Duper

As a fair word of warning, this contraption should be built high up and far away from any important or beloved structures. TNT tends to blast itself far away and cause some scary havoc. Regardless, players should start by placing a Sticky Piston with a slime block attached and go one block under and two blocks out, destroying the slime block underneath the one attached to the Piston.

Then, on the furthest slime block from the Piston, attach 3 Slime Blocks in an "L" shape to the side. It can be on either side, but players should mirror the design exactly, ensuring everything looks as it does in these screenshots.

Then, players must attach their fence/wall to the front side of the middle slime block, a piece of TNT under that same slime block, and a dead coral fan in front of the TNT. This machine could self-destruct if built incorrectly, so all parts must be placed appropriately.

Then the second to last step is placing a Detector rail right in front of the slime block on the piston face and putting a minecart on top of this rail. Again, if everything had been done correctly, the TNT shouldn't have exploded yet.

Pulling the lever will now prime the machine, causing it to extend outwards. This means the device should activate every other time whenever the lever is pulled. While this single manual duper can be helpful, there are ways to improve it.

Expanding and Automating

To start, the machine can be exactly mirrored on the other side (with a block of air in-between, so the slime blocks don't stick) to double the TNT output, and both can be controlled with a single line like this.

Then, two observers can be pushed together by a Sticky Piston to make a Redstone Clock that will constantly activate and deactivate the machine, producing a massive quantity of explosives.

This becomes incredibly useful in the Nether, where players can use this automatic machine to burrow out massive holes and uncover a large amount of Ancient Debris. This becomes even better when players utilize the Minecraft blocks that can't be broken by explosives, creating a platform at the bottom for TNT to explode and spread out, covering a massive area.