Well, first of all, there's the Apparatus of Kwalish to use as a base. My idea, and it works mostly from the point of view of an artificer-type:

1) Obtain some very good full plate; of a size larger than you if you prefer to sit, rather than wear. Adamantine would be ideal, but anything awesome would be good.

2) Enchant it with Animate Objects, as one would do for an Apparatus; instead of being a random attacking thingy, it's a full-on suit that responds to your commands.

3) If possible, bind it as an item familiar.