Rendering a model over the player without armor

Hey folks, just like the title says. Is there a way to render a model over the player like a biped armor model that fits the walk, swim, and crouch animations without using an armor slot? I did mess around with the curios plugin for a bit but couldn't get the model to line up when doing something like crouching or swimming. I'm not that well versed in Java coding but any help is appreciated!