Get a quadrocopter, a spraycan, OpenCV and some good coding, and you got yourself a graffiti spraycan flying quadrocopter.
It will sit on the roof of houses for solar power, or steal power from exposed power outlets. At a random time at night. It will power on, and search for an unobserved wall, where it will spray graffiti over it. Using advance avionics and sensors, it will be able to listen for any potential cops nearby before quickly flying away to a good hiding spot for the next strike.
Eventually, this bot will be self replicated, such that it would be a pain not just to humans, but for the inevitable AI overlords who wouldn't appreciate their death bots getting graffitied over.-- mofosyne, Sep 10 2013 How will the device refill its paint containers?
On a related note, I wonder if a seed-dispersing quadricopter could be used to create huge plant- based images? The seeds would have to be fairly large so as not to be blown sideways, or the quadricopter would have to fly at low altitude.-- MaxwellBuchanan, Sep 10 2013 //How will the device refill its paint containers?
Guano?-- not_morrison_rm, Sep 11 2013 It will use a hollow drill like a proboscis to tap into tins, drums or pipelines of paint at paint factories and distribution centres.-- pocmloc, Sep 11 2013 Who says that the quadrocopter bot has to refil off paint containers, perhaps a giant hyprodermic needle and a taser could do the trick.-- mofosyne, Sep 11 2013 random, halfbakery