Abstract: A mechanical part useful in various fields of application including plastic and metal processing is produced using a computer-aided design process including a preliminary break-down of the body of the part into elementary strata, followed by manufacture of the elementary strata, and reconstruction of the part. During break-down of the part, at least one fluid transport circuit, which is designed and modeled beforehand, is broken down into elementary chambers (20) in accordance with the break-down of the part. The elementary chambers are produced in the elementary strata (7i) forming the part during manufacture of the strata, and the fluid transport circuit is reconstructed during superposition and assembly of the strata.