| 摘要 |
The pyramid has a cardboard base (1) with an elastic rubber bracelet (2) by which the pyramid automatically unfolds as soon as it leaves its envelope. The pyramid has pre-grooved folding lines (8) which form zones of least thickness (8) around which the different walls (5) and triangular faces (6) articulate. A notch is located at each end of two walls (3) in the extension of the diagonal formed by the median fold (4). The notches hold the elastic in permanent tension. The walls and triangular faces are made solid by gluing legs (7) placed at the ends of the base walls and at the end of an edge adjacent to two triangular faces. The legs connect the base to the pyramid top.
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