Extra Armor Slots

So, I couldn't tell you exactly what mods, but around the internet I've seen a few mods that allow you to have extra armor slots. It's a little bit like the Cosmetic Armor, but what I want to do is make it so multiple layers of armor are visible. So say I make a shirt armor, and I also make a sweater armor... I want to be able to see the shirt under the sweatshirt. Is there a way to do this? Thanks.