An extrusion head for extruding a plastomeric or elastomeric material on at least two filaments having a diameter of the order of 0.1 mm. and having a high modulus of elasticity while maintaining a constant spacing between the filaments and a process for such extrusion. The head comprises a mandrel with a cylindrical portion and a frusto-conical portion, the mandrel having grooves equal in number to the number of filaments extending along the surfaces of both portions for guiding the filaments. The frusto-conical portion has channels between the grooves for feeding the material between the filaments. A die with an opening having parallel walls for guiding the filaments and having a conical surface spaced from the frusto-conical portion is mounted adjacent the latter to provide a space for flow of the material. A further element adjacent the die may be used to extrude further material over the filaments embedded in the material extruded therebetween.