A baseboard radiator having notched fins. The resinous porous article has an interconnected hole formed by molding a resin mixed with a pore-forming substance into said resin, and extracting said pore-forming substance from said molded article with a solvent which dissolves said pore-forming substance and does not dissolve said resin. The two end parts and the intermediate part exhibit, in cross section through a plane perpendicular to said the longitudinal axis, cross-sections having polygonal shapes centered on said longitudinal axis. Once this initial metal layer is formed, additional cobalt ALD layers may be completed to form a cobalt metal layer of a desired thickness. The seal member is releasably coupled to the distal end portion of the first elongate member.