Once the various constituent parts of the container are cut, two parts are joined as in FIG. 1, on the pattern designing table, by means of a 5-thread seam, additional parts being successively joined in this way on the sides thereof, until four parts are assembled, forming a cylinder or a trunk of a truncated pyramid. A square is then joined as in FIG. 2 by means of a 5-thread seam in the lower part of FIG. 3 and FIG. 4, or the smallest square detached from the trunk of the truncated pyramid produced. Finally, a container is produced, joining four isosceles trapeziums on the sides thereof and a square in the lower part, thereby joining all of the parts on one of the ends thereof FIG. 4. All of the seams are then reinforced by means of thermosealing (according to the model), using a conventional thermosealing machine at 220°-240° in order to melt the felt. A 1 cm hem is made by means of a linear seam, adding the tag of the product into said seam FIG. 7. The containers of more than 15 litres comprise a reinforcement in the upper part thereof FIG. 5, acting as handles. Inside the container is a piece of felt as in FIG. 6. Depending on requirements, the product can also be made with a 5-thread overlocking machine.