Abstract: A countertop assembly kit is designed for ease of assembly with a resulting superior appearance at minimal cost while meeting all functional requirements. It comprises some combination of the following items. A rigid substrate having pre-formed grooves in its upper and front surfaces. An upright member includes an underlying rib for fitting engagement with the upper surface groove for firm mounting on the substrate and an upper longitudinally extending groove in its upper surface. A finishing T-cap member of plastic material has a planar head and an integral downwardly projecting ledge for fitting engagement with the upper groove so as to be engaged with and coextensively overlie the upper surface of the upright member. A plastic backsplash member coextensively overlies the front surface of the upright member. A plastic countertop coextensively overlies the upper surface of the substrate while allowing for mounting of the upright member.