The sheets (1) and (2) are cut separately in rectangular shapes and with one of their corners recessed (1.2) and (2.4) and the sheet (1) slightly larger than the other one, double, on layer (2.1) an alignment of cylindrical lenses (2.2) which reflect images from the other internal sub-sheet (2.3), the two sheets (1) and (2) are superimposed; they are joined and their rims hooked together, in a tube (3) with the vertical upper recesses; a small flange (1.3) is configured at the top covering the rim of the sheet (2), except for the recess thereof, with one of the ends of the small flange (1.3) overlapping the other; the lip (1.4) is inserted in the stepped piece (4.1) of the bottom (4) of the container; the latter is flanged (4.2).