Method for applying an insert 40 of polymer material onto a support layer 30, 30a, comprising the following steps: providing a mould 10 comprising at least one base 12 and at least one cover 18; the base 12 and the cover 18 being suitable for defining with the facing surfaces 13, 17, when the mould 10 is closed, a mould impression 16 which is delimited perimetrally by a closing edge 14; spraying a polymer mixture M in the fluid state onto one of the two facing surfaces 13, 17 of the mould 10; introducing the support layer 30, 30a between base 12 and cover 18 of the mould 10 so that, when the mould 10 is closed, the support layer 30, 30a projects from the closing edge 14; pressing the cover 18 of the mould 10 onto the base 12; opening the mould 10 in order to remove the support layer 30, 30a and the associated insert 40; trimming the portion S of the polymer mixture M which, following the spraying and pressing steps, has flowed outside the external perimeter of the impression mould 16. Finally, the invention relates to a mould 10 which can be used to implement this method and the articles 20 which may be obtained by means of this method.