Abstract: This device comprising engaging and retaining means (1b), (1c), (1d), (1e) collaborating with the central hole in the disc, said disc engaging and retaining means being formed as an overhang over a circular central region (1) exhibited by the base (1), is notable in that the region (1a) has arrangements able, when finger pressure is applied to said means (1b), to allow them to retract in part only so as to cause simultaneous controlled tilting of the disc corresponding to its partial release from the base (1) so that it can be grasped by hand at the released part.