How do I duplicate items?

I just retrieved the Jagged Crown in Skyrim for Xbox 360, and see that it sells for 5000 gold. I heard that there is a duplication glitch in putting the item on a mannequin.

Anyone know how to do this? Where can I find one in the game? I do not yet have a house.

Requirements

• Must have completed Dark Brotherhood questline
• Must have got the Mannequin upgrade in the new Dark Brotherhood Sanctuary.

The Guide

Firstly, make sure you have the requirements stated above. Now, go to the sanctuary in dawnstar. Proceed to the room with the Mannequin. Click on the Mannequin to activate it. Press Square (PS3) or X (Xbox) to store your desired apparel into the Mannequin. Now, do NOT back out of the menu. Go back up to 'Apparel' on the mannequin and take your armour back out. Now, exit the menu and equip the armour that you had originally put in the Mannequin.

Next, quickly leave the Sanctuary. Once you have left, re-enter and go back to the Mannequin. You will notice that if you have done it right, the Mannequin will have your apparel equipped. Take it off him, and repeat if you want to keep getting sets of armour.

^{Source: http://skyrimforums.org/threads/slight-spoiler-guide-how-to-duplicate-apparel.825/}
Also, for PC, the console command player.additem DA750 (number you want goes here) will do exactly that; add the number you want of the crown in your inventory. Or you could do 000000f or just f, which is gold.

Another trick I've noticed that I would like to share is the inconsistency within the houses offered in the Hearthfire DLC. I'm unsure of how to properly do this, but I've cloned almost every set of armor I've had using the mannequin in the Lakeview Manor. As you know, the duplication glitch has been patched, but for some strange reason it can be achieved within these three following houses: Lakeview Manor, Windstad Manor, and Heljarchen Hall. As soon as you purchase one of these houses, it's imperative that you immediately put on any armor and/or clothing on one of the mannequins in any one of those selected houses (preferably in the armory). When exiting your house and arriving back, usually after quite some time you'll notice loading inconsistencies within the house. This can be seen by invisible mannequins and/or mannequins improperly placed in front of the pedestal. When this happens you want you want to remove whatever items you've placed on them quickly and exit the house. On arrival, those items will have reappeared. Once you have the Black Market power it's extremely useful for unloading valued cloned items such as the Jagged Crown.