Senseless Drawing Bot -- yes, that's this robot's given name -- is a graffiti machine, even if its creators So Kanno and Takahiro Yamaguchi wouldn't want to call it that as evidenced by their Tumblr page name "This Is Not Graffiti."
Watch its free-swinging pendulum arm create mesmerizing patterns of swirly spray paint:
The Senseless Drawing Bot was featured at an exhibition "UTOPIA no OSHIRASE" in Tokoyo. As IEEE Spectrum notes, "humans are not allowed to do this"; perhaps it's only OK when a robot does it.
And the creators don't want the Senseless Drawing Bot to be considered for graffiti, because they have a robot for that purpose: "a device for graffit." Watch it do some serious wall damage that isn't nearly as soothing as Senseless Drawing Bot's execution: