solved metal 3d printing

a metal 3d printer uses energy to melt metal wires 

while it dispenses them 

and the metal 3d printer dispenses multiple hot metal wires 

and a few cold metal wires 

the hot wires melt 

and the cold wires absorb the heat from the melted metal 

so that the cold wires melt too 

while the previously melted metal cools down faster 

and a few extra cold metal wires 

could be dispensed at the same time 

in order to become rebar in the 3d printed metal mass 

in a similar way to how rebar is used in concrete in order to reinforce it 

optionally, a cold metal powder 

could be sprayed on the melted metal 

so that the metal powder melts on contact 

and creates an outer layer on the 3d printed metal 

while the metal powder absorbs heat from the metal powder 

so that the melted metal cools faster 

such a system would speed up metal 3d printing significantly 

which would make it more usable in industrial production