bengeddes: You don't place the item into the mold. You don't do anything with the item. You need to "activate" the mold and then use it on an item.
1. Place Helwax Mold in quick slot.
2. Exit out of the inventory screen.
3. Left click the Mold in your quick slot to "activate" it.
4. It will automatically open your inventory, and your cursor will become a pointer with "?"
5. Left click on the item you wish you to duplicate.
6. You will be prompted to confirm that you wish to duplicate the item, click Accept or Cancel.
7. If you click Accept another prompt will inform you of success and that the duplicated item has been placed in your stash.
So which step are you stuck on? Are you saying you did all that and no duplicate is created?
Never managed to get step 3... the wretched thing kept transporting itself or the weapon to inventory.... your input was very helpful... thanx...