Fold the narrow areas close to the top and bottom edges if the fabric towards the middle, so that the edgess are lined up, as shown on the second photo.
Lay the lager plastic parts under the fabric, with the holes for attaching the elastic band towards the outer edges. Now place the smaller plastic parts, one on each side, near the edges of the fabric.
The small studs should face downwards, towards the fabric surface.
Clip the plastic parts together through the fabric by pressing until it is fixed between the two parts. The fabric is pushed down into the large part.
Attach the enclosed elastic bands through the holes at the sides of the larger plastic parts. These can be used to fix the mask securely over your ears. Fold out the edges of the fabric over nose and throat when you put it on.
Now you can wear your self-assembled mask4all.
Should the mask be too tight or too loose, the clips can be loosened and repositioned. Manual streching of the elastic bands before wearing may also help to improve the fit.