S , ▁poly phen yl s ulf one ▁( P PS U ) ▁and ▁high ▁impact ▁pol yst y rene ▁( H IP S ). ▁In ▁general , ▁the ▁polym er ▁is ▁in ▁the ▁form ▁of ▁a ▁fil ament ▁fabric ated ▁from ▁vir gin ▁res ins . ▁There ▁are ▁multiple ▁projects ▁in ▁the ▁open - s our ced ▁community ▁aim ed ▁at ▁processing ▁post - consum er ▁pl astic ▁waste ▁into ▁fil ament . ▁These ▁involve ▁machines ▁used ▁to ▁sh red ▁and ▁extr ude ▁the ▁pl astic ▁material ▁into ▁fil ament ▁such ▁as ▁rec ycle b ots . ▁Additionally , ▁flu or opol ym ers ▁such ▁as ▁P TF E ▁tub ing ▁are ▁used ▁in ▁the ▁process ▁due ▁to ▁the ▁material ' s ▁ability ▁to ▁with stand ▁high ▁temper atures . ▁This ▁ability ▁is ▁especially ▁useful ▁in ▁transfer ring ▁fil aments . ▁ ▁Metal ▁and ▁glass ▁may ▁both ▁be ▁used ▁for ▁ 3 - D ▁printing ▁as ▁well , ▁though ▁they ▁are ▁much ▁more ▁expensive ▁and ▁generally ▁used ▁for ▁works ▁of ▁art . ▁However , ▁the ▁development ▁of ▁W A AM ▁( wire ▁arc ▁add itive ▁manufact uring ) ▁has ▁reduced ▁the ▁costs ▁of ▁metal ▁ 3 - D ▁printing . ▁ ▁F DM ▁is ▁somewhat ▁restricted ▁in ▁the ▁variation ▁of ▁shapes ▁that ▁may ▁be ▁fabric ated . ▁For ▁example , ▁F DM ▁usually ▁cannot ▁produce ▁stal act ite - like ▁structures , ▁since ▁they ▁would ▁be ▁un supported ▁during ▁the ▁build . ▁Otherwise , ▁a ▁thin ▁support ▁must ▁be ▁designed ▁into ▁the