Patent ID: 6997771

Claim:
A set of elements for building easily disassembled and collapsible structures, each element comprising: a flat structure a having a front and a rear surface and at least one edge defining a perimeter common to the two surfaces; and a plurality of protrusions on at least one of the surfaces, each protrusion having a body portion extending away from the element; wherein the body portions of one or more protrusions, when in abutting contact with an edge of another element, anchor the other element by preventing the edge of the other element from sliding beyond the point or locus defined by said one or more protrusions; whereby structures are assembled by leaning a first element against a second element and anchoring the first element against sliding by one of placing an edge of the first element in abutting contact with at least one protrusion of a third element and anchoring the edge by placing it on a suitable non-slip surface and balancing an element on top of one or more other elements; at least one of the elements comprising a rectangular card having planar front and rear surfaces and four linear edges, said at least one element being provided with solid protrusions on both surfaces, the body portion of each protrusion being tapered inwardly as it extends away from the front and rear surfaces of the element, and the protrusions being arranged in linear groups and regularly spaced to form rows of substantially uniform shape and size alternately placed on the two surfaces thereof and the corresponding protrusions of each row being linearly arranged to form columns.