3D printing in its current guise is pretty impressive, but also limited by its use of plastic. An affordable 3D printer that uses metal would be a major step up in practicality, which is exactly what this team is hoping to achieve by mating a MIG welder to a conventional 3D printer.
The team from Delft University is following in the footsteps of researchers from Michigan Tech, who last year also created a 3D printer that used a welder. That project, however, laid down sheets of steel, which were then combined with the welder. Delft's approach is different: it feeds a small spool of wire to the welder, which is then laid down layer by layer to create an object, exactly like in the plastic Prusia i3 it's based on.
At this stage, though, performance isn't really close to plastic printers: the 3D welder feeds wire at a rate of 300mm/minute, compared to the 10,000mm/minute you can expect from a decent 3D printer. Still, with the open-source nature of the project, and the relatively low cost, this is promising attempt to make metal 3D printing affordable. [3D Print]