a plastic extrusion mechanism having a die head primarily for use in a melt - blown process with the head formed in two mating parts respectively having first and second chambers therein with separate plastic heaters and pressure delivery extruder screws connected thereto and an insulated wall between the chambers with the lower end of the wall having slots leading to passages and alternate passages communicating with the first or second chambers and the passages leading to small extrusion openings for extruding microfibers of plastic and high velocity air directed against the microfibers for attenuation , and a traveling porous surface beneath the die head for receiving the fibers which are formed of plastic from the first chamber having a first physical characteristic and the second chamber having a different physical characteristic .