By processing triangle or square pyramid shaped indents on a flat sheet following regular plane tiling patterns, panels with periodical indents are manufactured. By setting this panel (as top panel) on reversed one (as bottom panel), and gluing them at the apexes of pyramids to nodal points of the tiling patterns of bottom panel, highly rigid core panels are newly developed. The basic model named "dia-core" corresponds to the space filling models by two tetrahedra and one octahedron. Besides, varying the geometric patterns which appear on their surfaces, various modified models are devised. This pattern variation is known as Archimedean plane tiling in geometry.