That's not R5-D4's brother, it's a modded Wiimote that a German student envisions for use in a virtual graffiti world.
Martin Lihs, student at Bauhas-University in Weimar, built the "Wiispray" for his thesis. He wants the wall to encourage graffiti artists to express themselves without the artistic encumberances of balancing on a highway overpass railings, getting chased by railroad police, or, like getting arrested.
Sounds fun and creative but people tag up real walls for a reason — real people see 'em. All the commissioned murals, coffee table books and contests for graffiti artists provide real recognition to, but not like getting up on a warehouse wall. The essential act of graffiti is painting where you're not supposed to paint, right?