A static mixer - of the type which may be introduced in a pipe or associated with the same to form a portion of said pipe, so as to homogeneously blend a fluid flowing in the pipe, without using rotating parts - comprises a cylindrical outer portion (2) and a blending internal structure (3) consisting of multiple elements having planar or curved surfaces, variously arranged and angled to the flow direction. The inner structure (3) and the outer cylindrical portion (2) are radiused and connected to one another, without discontinuities or mechanical joints, by a single sintering process of a plastic or metal powder material with a successive-layer laser.