▁of ▁material ▁which ▁hard en ▁immediately ▁to ▁form ▁layers . ▁A ▁fil ament ▁of ▁therm op last ic ▁or ▁other ▁low ▁mel ting ▁point ▁material ▁or ▁mixture ▁is ▁fed ▁into ▁an ▁extr usion ▁no zz le ▁head ▁( 3 D ▁printer ▁extr uder ), ▁where ▁the ▁fil ament ▁is ▁he ated ▁to ▁its ▁mel ting ▁temperature ▁and ▁extr ud ed ▁onto ▁a ▁build ▁table . ▁More ▁recently , ▁f used ▁pel let ▁de position ▁( or ▁f used ▁particle ▁de position ) ▁has ▁been ▁developed , ▁where ▁particles ▁or ▁pel lets ▁of ▁pl astic ▁replace ▁the ▁need ▁to ▁use ▁fil ament . ▁The ▁no zz le ▁head ▁he ats ▁the ▁material ▁and ▁turns ▁the ▁flow ▁on ▁and ▁off . ▁Typ ically ▁ste pper ▁mot ors ▁or ▁ser vo ▁mot ors ▁are ▁employed ▁to ▁move ▁the ▁extr usion ▁head ▁and ▁adjust ▁the ▁flow . ▁The ▁printer ▁usually ▁has ▁ 3 ▁axes ▁of ▁motion . ▁A ▁computer - a ided ▁manufact uring ▁( C AM ) ▁software ▁package ▁is ▁used ▁to ▁generate ▁the ▁G - Code ▁that ▁is ▁sent ▁to ▁a ▁micro controller ▁which ▁controls ▁the ▁mot ors . ▁ ▁Pl astic ▁is ▁the ▁most ▁common ▁material ▁for ▁such ▁printing . ▁ ▁Vari ous ▁polym ers ▁may ▁be ▁used , ▁including ▁ac ry lon it rile ▁but ad iene ▁sty rene ▁( AB S ), ▁poly car bon ate ▁( PC ), ▁poly la ctic ▁acid ▁( P LA ), ▁high - dens ity ▁poly eth yl ene ▁( HD PE ), ▁PC / AB