Abstract: Each of a plurality of rectangular sheet-like plates of rigid material has a plurality of square holes formed therethrough in rows and columns. Each of a plurality of anchoring strips of rigid material is of elongated narrow rectangular configuration with a point formed at one narrow end thereof for penetrating the ground. Each of the anchoring strips has a plurality of square holes formed therethrough in rows and columms. A plurality of selectively openable and closable rings have a diameter sufficient to accommodate two of the plates and passable through the holes thereof. Each of a plurality of bolts has a head with an extending square cross-sectioned shank portion fittable in the holes of the plates and strips whereby the plates are securable to each other via the bolts and wing nuts in any desired structural combination.