I need to stick a concave object on the surface of a convex one ( ellipsoid ) without intersection. the coordinates of the concave one on the ellipsoid should be animate-able and the heading of the concave one too. How can I do this without physics in sop context ? I guess I would need something like collision detection in sops. ATM i am trying to use the ray sop, rivet and sticky but they dont really deliver what I am after. Anyone done something similar ?

I just stumbled upon the stick sop. Can this one maybe used my purpose ?

To clarify i need something like an interactive rig for a hat which has to slide on the head on a bald man, but not as an offline simulation, but an interactive tool.