D ▁printing ▁or ▁rest oring ▁metal ▁parts . ▁▁ ▁Metal ▁wire ▁processes ▁ ▁Las er - based ▁wire feed ▁systems , ▁such ▁as ▁Las er ▁Metal ▁De position - wire ▁( L MD - w ), ▁feed ▁wire ▁through ▁a ▁no zz le ▁that ▁is ▁m elt ed ▁by ▁a ▁las er ▁using ▁in ert ▁gas ▁shield ing ▁in ▁either ▁an ▁open ▁environment ▁( gas ▁surrounding ▁the ▁las er ), ▁or ▁in ▁a ▁se aled ▁chamber . ▁Electron ▁beam ▁free form ▁fabric ation ▁uses ▁an ▁electron ▁beam ▁heat ▁source ▁inside ▁a ▁vac u um ▁chamber . ▁ ▁It ▁is ▁also ▁possible ▁to ▁use ▁conventional ▁gas ▁metal ▁arc ▁w eld ing ▁attached ▁to ▁a ▁ 3 D ▁stage ▁to ▁ 3 - D ▁print ▁met als ▁such ▁as ▁steel ▁and ▁al umin um . ▁Low - cost ▁open ▁source ▁Rep R ap - style ▁ 3 - D ▁printer s ▁have ▁been ▁out f itted ▁with ▁Ar duino - based ▁sens ors ▁and ▁demonstrated ▁reasonable ▁met all urg ical ▁properties ▁from ▁conventional ▁w eld ing ▁wire ▁as ▁feed stock . ▁▁ ▁Pr inter s ▁▁▁ ▁Indust ry ▁use ▁▁ ▁As ▁of ▁October ▁ 2 0 1 2 , ▁add itive ▁manufact uring ▁systems ▁were ▁on ▁the ▁market ▁that ▁r anged ▁from ▁$ 2 , 0 0 0 ▁to ▁$ 5 0 0 , 0 0 0 ▁in ▁price ▁and ▁were ▁employed ▁in ▁indust ries ▁including ▁a eros pace , ▁architecture , ▁autom ot ive , ▁defense , ▁and ▁medical ▁rep lac ements , ▁among