Using a “blinds-your-eyes-forever”-grade laser, a bright beamer, a security camera and some open software (complete list and instructions) you can virtually tag any build you like (and can park your van in front of).
This is a brilliant example of what can be achieved using (sort of) standard equipment, creativity and some clever software. The video below shows the best parts of the Amsterdam event. Even cops joined the show and had their fun using the L.A.S.E.R. tagger. And the best part: you cannot be busted for this (except for using a laser this strong).