How can you duplicate diamonds in minecraft? In 1.15.2
That depends on where you want to duplicate.
In a single player world, this should be difficult, but there are certainly still some security holes in the spigot on 1.15 servers.
On a server with mod
Afaik the item frame glitch is still in 1.15.
If you place an item frame on the back of a piston and put an item in, you will get it twice if you break the item frame exactly when the piston goes back.
So that's how. Several items go with a Shulker box.
Exactly the other way around:
In single player Super Duper Easy, but Spigot / Paper has fixed almost all the gaps.
Mod? Which mod? Or even a mod pack? Write in.
The music box is so that the timing is better, but not necessary.
Mod create
When you dropper your slides into the lava I heard that there would be more
