Piston duplication

Replicate:

-Make a 4 by 4 square 

-Put the items like in the photo

(in case fails to upload the photos)

First layer:

[B] [G] [SPv] [B]

[B] [SP>] [A] [SPv]

[B] [B] [A] [A]

[A] [B] [O] [A]

Second layer:

[R] [R] [Rep>] [R]

[Repv] [R] [A] [A]

[R] [Comp↑] [A] [A]

[A] [L] [A] [A]

B= Block

G = Glass

SP = Stiky piston

A = Air

O = Obsidian

R = Reston dust

Rep = Repeater

Comp = Comparator

v = south

> = east

< = west 

↑ = north

 

Randomly the item of the piston will appear like it had broken but the three will still be there, even if you switch to survival.