A set of elements used for building easily disassembled structures includes a plurality of building cards. At least one surface of each card is provided with protrusions extending normally therefrom. When an edge of a first card is in abutting contact with one or more protrusions of a second card, the one or more protrusions prevent the first card from sliding beyond a point or locus defined by the one or more protrusions thereby permitting the first card to be stably leaned against a third card, and so on, to create supported structures constructed from a plurality of the building cards.