HERE'S THE VIDEO HOW! :D



This is how to dupe the items in text:
Regular MC:
-drop the items you want to dupe
-press Esc then press save and quit
-go back to the world and pick up the items you dropped
-open your inventory and exit out of minecraft
-open minecraft up and go to the world and enjoy your duped items.
Tekkit (Red Matter Furnace):
-open the red matter furnace
-put the item in the lower right spot in your 3x9 inventory
-hold down shift and click it
-repeat to get more items
Tekkit (alchemical chest):
-put the item in the alchemical chest
-have someone break the chest while your inside of it
-take the "fake" item out and put it in an energy condenser to make infinite items