A disc shaped, unitary body with a flat top surface mates against a tripod head. An upper side annular surface defines a fanned array of threaded bores on radial axes for receiving and supporting extension rods leading to suction cup fasteners. A lower side surface of frusto-conical contour, converging downwardly, depends from the upper side surface and defines a fanned array of threaded bores on axes angled outwardly and downwardly. A bottom face is a planar ring that defines vertical bores distributed around the ring. A central cavity wall is configured as an upwardly tapering conic frustum, connected at its lower end to an inside edge of the bottom wall. The cavity wall defines a fanned array of threaded bores on axes angled inwardly and downwardly. The top of the cavity wall defines a countersink.