This mod allows the break down of most unenchanted weapons and armor, and most clutter.

Metallic items can be broken down at a smelter and non-metallic items can be broken down at tanning racks. Items made of bone, like bonemold armor, forsworn weapons, and skulls, can be ground down into bone meal at a Grain Mill. Gems can be pried out of jewelry and circlets at a tanning rack.

Pretty much every unenchanted non-unique weapon and armor can be broken down. Excluded is Fur.

Yield amounts vary between items and, for the most part, you're not gonna get back quite as much as you put in. This isn't always the case, especially when it comes to items that can't easily be exploited, such as Daedric items.

Items will only show up at the smelter or tanning rack if you have at least one of the item and don't currently have it equipped. Due to some engine voodoo that is beyond my control, items that you have enchanted can be broken down and they will appear as just any normal item in the smelter. You should exercise a bit of caution when using the smelter while your enchanted weapons and armor are in your inventory.

Here's a list of what can be broken down. It's not exhaustive and some things can be broken down that don't appear here:

Hide items
Leather items
Guard armor
Stormcloak armor
Iron Items (includes clutter)
Steel Items
Ancient Nord items (includes honed and armor)
Imperial items
Bonemold armor (includes improved)
Silver Items (includes clutter)
Hearthfire building materials
Dwarven items (includes clutter)
Elven items
Forsworn Armor and Weapons
Skyforge Steel weapons
Companions armor
Orcish items
Falmer items
Dawnguard items
Vampire armor
Blades items
Chitin armor
Nordic items
Nord Hero items
Scaled armor
Steel Plate armor
Glass items
Ebony items
Stalhrim items
Daedric items
Dragon armor and weapons

To get a better idea of what this mod allows to be broken down (and to see my numerous failures) you can check out the changelog in the "changes" tab.