First off u need a pickaxe and a sword, furnace, some extra cobblestone, and (1) of the item that u want to duplicate, now u need to set down ur furnace then put in the item u want o duplicate as ingredient. Then u jump up on ur furnace and start minning it with ur pickaxe and when its ab out 90% done switch fast to ur sword then the furnace should disapper then re-apper and then jump down fastly and highlight the item and hold down the A button until the furnace disappers and if u did it correctly there should be 2 of ur items on the floor pick one of them up and put it in ur chest and go back to the other one and pick it up and open ur chest and then start holding down the x button on ur inventory and u should have unlimted items (that u choose) until u exit ur chest. Plz give me a thanks if this was helpful And sorry for the bad grammer