Abstract: A tool for applying a binding agent and/or a filler is provided. The tool enables convenient and accurate application of the binding agent and/or the filler, such as adhesive or mortar for wall panels and grout between wall panels. The tool comprises a body including a front surface, a rear surface, and a plurality of edges circumferentially extending around the body, each of the plurality of edges defining a junction of the front surface and the rear surface. One of the plurality of edges comprises a plurality of teeth extending away from the body. The teeth may comprise a flat face. One of the plurality of edges may comprise a protrusion. One or more rounded corners may be circumferentially disposed around the body between two proximal edges.