Blocks with detachable cap plates having additional mating connecting means

Claim 1

An interlocking construction element for use in building vertically and horizontally comprising: a closed frame having a plurality of sides one of which defines a basic length and opposite open ends, at least one said end having its surface lying in a plane; connector means for coacting with similar connector means of a similar element, said connector means including a tongue and groove integrally formed on at least one of the sides of said frame and projecting in planes inclined with respect to said planar surface of said frame; said tongue and groove each having a trapezoidal cross-section, said connector means being arranged in a regular manner on said side to correspond with said basic side length; at least one of the open ends of said frame being covered by a cap plate detachably engageable therewith by means of locking means on one major surface thereof in the form of sloping latch elements frictionally engageable with the interior side surfaces of said open frame, said cap plate having, on its surface opposite said one major surface, connector means for mating with said connector means of said construction element to connect one of said construction elements thereto.