Note, this may not work if your game was patched to fix the cloning item glitch. This glitch will also permanently alter your game.

First of all you need an enchanted armor, with a stat that you want to lock onto yourself PERMANENTLY, such as the ability to breathe underwater or spell absorption of some level.

Equip a bow and two or three arrows (the number of items you want to make works with more too). Draw the bow completely back, then bring up the menu. In here you should try to "Unequip" the arrows, it will click and tell you that can't do so while attacking, then you move over to the armor you want to copy and drop it.

Then exit the menu. You should hear the arrow release and a group of armor should clatter to the floor in front of you (some places can't duplicate items, but the "My Bruma House" seems to work wonders for me).

Pick up two of the enchanted armor, and equip one of them. Then draw back the bow with arrows (to do another duplication "un"-arrow and drop item), when you choose to drop this time, select the unequipped copy of the enchanted item and you will see the computer did a mental goof here. It dropped the equipped armor instead of the copy.

Any increases or enchantments on the equipment will be considered active, but you can no longer wear equipment in that area.