The present invention is directed towards a cosmetic assembly, of use for the treatment of keratin fibres, comprising a cosmetic composition having a melting point of between 40° C. and 120° C., and comprising at least 15% by weight of meltable compound(s), relative to the total weight of the composition； and a device (1) comprising a mould (2), the mould (2) comprising at least one cavity (5), into which or each of which at least one of said fibres can be at least partially introduced, for the purposes of moulding said composition onto at least one part of said fibre(s) present in the cavity or cavities (5). The present invention is also directed towards a process for cosmetic treatment of one or more keratin fibres.
