Sell the items to get as much gold as desired. Repeat this process as many times as desired. You will have all of the items and weapons you dropped back in your inventory, plus all of the items and weapons you dropped will still be on the ground. Instead, press the PS button, and choose to go to the dashboard. Once you have finished dropping the items, do not leave your inventory. Then, drop the items and weapons you want to duplicate. To duplicate crafting materials and weapons, enter another player's game online or through system link.