Abstract: A cardboard three-dimensional tree comprises: two primary substantially triangular sheets and four secondary substantially triangular sheets, each having an apex, a base edge opposed to the apex, and two side edges connecting the apex and the base edge. A first primary sheet has a primary slot extending downwardly from the apex and a second primary sheet has a primary slot extending upwardly from the base edge and engageable in the downwardly extending primary slot defined in the first primary sheet. Each primary sheet has two secondary slots extending upwardly from the base edge. Each secondary sheet has a primary slot extending downwardly from the apex and engageable in one of the secondary slots defined in the primary sheets. The primary and the secondary sheets are engageable in an interlocking intersecting relation at the slots and cooperating to form a self-standing generally substantially triangular three-dimensional structure generally in the form of an evergreen tree.