Pact of Iron

You can create an eldritch bond with a suit of light or medium armor by performing a special ritual with it over the course of 1 hour, which can be done during a short rest. You can then dismiss the armor, shunting it into an extradimensional space from which it will appear again whenever you use your action to summon it. When you summon your pact armor, you can also don it instantly as part of the same action. While you are wearing it, your pact armor weighs nothing, you are proficient with it, and it never imposes disadvantage on your Dexterity (Stealth) checks. Your pact armor appears to be made out of whatever material you choose, from mundane black iron to fantastical configurations of smoke and glass.
You can make magical armor into your pact armor, as long as it is not an artifact or a sentient item. Magical armor retains its properties while it is your pact armor.
The armor ceases being your pact armor if you die, if you perform the 1-hour ritual on different armor, or if you use a 1-hour ritual to break your bond to it. The armor appears at your feet if it is in the extradimensional space when the bond breaks.