Minecraft wiki entry for Block_and_item_duplication, associated text: The recommended build is not automatic. For the recommended build, you will need at least 1 switch, 1 sticky piston, a chest, 10 redstone repeaters (all set to maximum delay), 2 redstone dust, and a button, though there are simpler(thus cheaper) versions that require only a sticky piston, a chest and a button. The instructions are as follows: