As of 1.16, TNT dupers seem on their way out. Why write about them now? Last Chance to See. In the next year or so, I plan to dupe all the TNT and tunnel all the Bores. #NewYearsResolution

How do TNT Dupers work?

A BUDed TNT gets a block update immediately before it is moved by a piston (directly or indirectly). The block update primes the TNT, it becomes an entity but the TNT block is not deleted - it becomes Block 36 and continues being moved by the pison.

Since 1.13.1, a Coral Fan is typically used to give this block update, although for stationary dupers you can just do it with a redstone circuit.

The position of the coral fan is important - all blocks in the duper are moved in the same game tick, but the coral fan has to move first in that game tick.

Ray Works has a good video about this: It’s BACK! 1.13.1-1.16.3+ TNT Duping | vanilla survival

Because the TNT is BUDed, you must be careful not to give it block updates. I.e. no placing or destroying any of the 6 immediately neighboring blocks. Redstone dust gives block updates up to 2 blocks away!

You also can not just build the duper in its working form. As soon as you place the TNT block or put the minecart on the powered rail, the TNT is primed by the block update. You either have to push in the minecart and rail with a piston, or arrange for the TNT to be pulled or pushed in position on the first activation.

The Mytteri Dupers

Popularized by Ilmango’s 1.13.1 World Eater video, if you only know one TNT duper - it is this one. Lots of videos about it, if credit is given it is usually to Ilmango. Ilmango says that Mytteri came up with the design.

This family of dupers dupes falling TNT, either on push (the most well known one), on pull (my favorite) or in both directions. The TNT is below a slimeblock, so it does not hop up which gives you extra time. Also there are no slimeblocks next to the TNT in the main direction of travel, this lets you align the falling TNT with 2 walls and a fence gate. This is great for stationary farms.

The Kades Duper

This variation is by Kades. It dupes on pull.

  • Easy to figure out the correct position
  • Easy to assemble and re-assemble
  • Exact alignment with 2 walls and 1 open fence gate

Just put the TNT where you want it to fall and build the shape from there. First push will grab the TNT, first pull will dupe.

To re-assemble if you lost the TNT or because you used a placeholder block until the timings seem ok: Put the TNT below the wall, first push will grab the TNT, first pull will dupe.

There is a 2-way option by putting an additional block behind the slimeblock that holds the coral fan.

The Mytteri Duper

The famous one. Dupes on push. For a stationary farm I prefer the Kades duper, for a flying machine I would consider other designs first.

  • Easy to assemble, can be reassembled
  • Exact alignment with 2 walls and 1 open fence gate

When building, the TNT goes 1 position in front of it’s fall position. First push will grab the TNT, next push will dupe.

Can be re-assembled by knocking out the connecting slimeblock (behind the minecart in the image) when the piston is extended, then retracting the piston. Put TNT below wall, replace slimeblock. First push will grab the TNT, next push will dupe.

Other Variations

  • Two-Way Duper: have a coral fan in front and in back of the TNT
  • Ilmango 5 Way TNT Duper: Pull duper with additional slimeblock and additional walls. Can be pushed and pulled on top slimeblocks, or pushed against the minecart.

Rays Works Slim Duper

These are by Rays Works according to his video linked above.

They are only 1 block wide, so you can pack them tightly. The height can be a problem though.

Rays Works Slim Push Duper

  • Easy to assemble and re-assemble
  • Good for controlling fall height with honey blocks

From the fallchute, figure out the position for the wall and build the shape. TNT below the wall. Push once to assemble, next push will dupe.

Borkon likes Controlling TNT with honey. Me, I am not entirely convinced. I like the more fine-grained control of pistons or waterlogged trapdoors.

In any way his formula is: 4 honey blocks, top block 1 below tnt, with 3 blocks of air between honey and duper. TNT will explode 15 blocks below TNT position.

Variations

By knocking out the bottom 2 slimeblocks and sticking the coral fan on the remaining slimeblock below the TNT, you get a pull duper. The TNT falls instead of shooting out.

Eta740 “Most Versatile” Dupers

  • Good for Tunnel Bores

This one has so so many variations, watch Eta740’s video on Standard TNT Dupers.
I am showing the Tunnel Bore variation, which is not as nice to assemble as the other variations - but it is the most useful one.

Not so easy to align, so other options are better for stationary farms. But it’s only 3 blocks high and can shoot out the TNT which makes it an option for Tunnel Bores - Ilmango uses it in his Industrial Tunnel Bore.

Ilmango Honey Dupers

  • Good for Tunnel Bores

Ilmango has several TNT dupers that use honey instead of slimeblocks, of particular interest is the design for his Honey Tunnel Bore, because it is only 3 blocks high and has no sticky blocks in bottom position.

In Peaceful Challenge #6 Ilmango shows the design and also the design process.

Borkon uses it in his Ridiculously Simple Tunnel Bore - it needs the small size (and lack of sticky blocks in bottom position) of this design.

Mytteri 2-way Duper

Our man Mytteri really likes TNT Dupers.

  • Easy to assemble and re-assemble
  • Maximum Bang for making smallish holes

If you knock out the bottom front wall, you get a push duper. If you knock out the bottom back wall, you get a pull duper.

This flexibility can be used to build flying machines relatively close to the ground. Start with TNT only on one side, duping only backwards. Once the ground is further away, add second TNT. Finally dupe in both directions.

For me this works with 4 dupers at a time 12 blocks up. More than that/closer to the ground and you’ll be re-building a lot. Still a better love story than Twilight.