Duping the most valued items and distributing is the most effective. Infiltrate Pay to Win servers (Not Endorsed): Servers that violate the EULA by selling in-game items for real money can be duped and sold.While a decent, safe and consistent method of getting exp, building an Enderman Farm is faster. Duplicate Enchanted Equipment: combined with a grindstone, you can farm an infinite amount of EXP by removing enchantments from duplicated enchanted gear.Use this to duplicate blocks in excessive quantities. Duplicate Shulker Boxes (with items inside): theoretically you can duplicate both the shulker box and the items it contains, since that info is stored within the shulker box itself.Duplicate in bulk for items/blocks that will be used in large quantities. Duplicate Enchanted tools / Blocks: You'll never have to worry about running out of your tool / block of choice, since you can just duplicate them as well.Again, it is important to leave some stock as backup you never know if you need more.
This page seeks to teach you how to clone items and blocks without building a separate farm for them, in vanilla Survival mode. When this happens, the contraption will cease to work. Bugs of this nature may be fixed at any time without warning.