Okay, get 1 of the item you want, step in the water and place the item in a crafting table you will float through the portal and 2 of the item will drop out too, to first one will be normal but the second one is like a creative item, you can use it to place as many items in your inventory as you want :D
Note: you have to go into your invent and move the first one you picked up before you can pick up the second creative style one :)