Disclosed is an inset for a panel in the form of a pad or disk for holding supporting the weight of the panel and holding it against a back surface without any means of support for the panel being visible. The insert comprises; one or more spiral shape arms which spiral(s) radially inwards from a perimetral rim inwards toward the center of the insert where the arms have a connector to connect to mounting screw, bolt or rivet. Also disclosed is a panel wall assembly covering a back surface with a panel, comprising: the panel held face to face with the back surface by an out-of-sight insert inset in the panel; a mounting screw/bolt/rivet with a head-flange which protrudes from the back surface; and the insert comprising a connector connected to the head-flange of the mounting screw, bolt or rivet.