TARTU, Estonia (Reuters) — Mihkel Joala wants to add a splash of color to the cities of the world. To do that the Estonian inventor has created a robotic five-color spray-painter that he says can produce murals 100-metres tall on buildings. With it, Joala says he is ready to break world records. To test his prototype, Joala’s startup company Sprayprinter decided to print one of the tallest buildings in Tartu – the chimney of a […]