Although 3D printing in metal is advancing on an industrial scale, it’s not quite at the level of widespread DIY efforts. Unless you have a robotic welding arm handy.Designer Joris Laarman created the awesome machine in the video above, which effectively 3D prints metal lines in any direction and without any support structures, all with a satisfying creaking sound. The robotic arm basically draws freeform and the welding machine on the end adds molten metal a little bit at a time, like a giant automated 3Doodler.On his website, Laarman explains that the work-in-progress tool can print in steel, stainless steel, aluminum, bronze or copper, and follows on from his earlier robot resin printer. “The combination robot/welding is driven by different types of software that work closely together,” the project page explains. “This will eventually have to end up in a user friendly interface that allows the user to print directly from CAD.”Design blog Dezeen reported that Laarman is currently making a bench using the technique for an exhibition of his work, and pointed out that the advantage of his method over other metal 3D printing tools is that it can print objects on a large scale. You might be able to make a gun with laser sintering, but good luck printing whole architectural structures.The robot arm also isn’t deterred by such quibbles as lumpy surfaces, or gravity. “This method makes it possible to create 3D objects on any given working surface independently of its inclination and smoothness in almost any size and shape,” Laarman writes.Looks like our futurescapes may be drawn by oversized 3D printer robot arms, a proposal that couldn't include more of my favourite things.