I was wondering what efficient techniques are out there for mapping collision filtering between various bodies, sub-bodies, and so forth.

I'm familiar with the simple idea of having different layers of 2D bodies, but this is not sufficient for more complex mapping:

(Think of having sub-bodies of a body, such as limbs, collide with each other by placing them on the same layer, and then wanting to only have the legs collide with the ground while the arms would not)

This can be solved with a multidimensional layer setup, but I would probably end up just creating more and more layers to the point where the simplicity and efficiency of layer filtering would be gone.

Are there any more complex ways to solve even more complex situations than this?