Abstract: For manufacturing articles of plastics, rubber or any other material a mold or die assembly comprising a mold or die base assembled from repetitive modular standard elements consisting of substantially "ready to use" interchangeable base plates is provided by the invention.The base plates are prefabricated by high-precision castings or galvanoplastics or any other similar high-precisious non-cutting method of manufacture.At least two of such base plates are, as mold or die plates, provided with a pre-determined number and arrangement of finished to sized, prefabricated cylindrical bores or piercings of any non-circular, mainly polygonal cross-section. Each of said bores or piercings is capable of fittingly receiving an interchangeable mold or die insert carrying the individually designed (negative) mold or die cavity surface for forming the particular article(s) to be manufactured.