Abstract: A system for molding and assembling a fluid spray device, said system comprising two multi-cavity molds (B, C; B?; C?) for molding two different parts (100, 200) of said fluid dispenser device, the system being characterized in that the first part (100) is a spray head and the second part (200) is an insert for assembling in said spray head (100), said system comprising means for assembling parts coming from each of the cavities of the first multi-cavity mold (B; B?) in pairs always with parts coming from a corresponding respective cavity of said second multi-cavity mold (C; C?), such that the same insert (200) is always assembled in the same spray head, thereby guaranteeing constant spraying performance for each dispenser device assembled from the same pair of cavities.