The stunt on the grounds of Parliament was designed to raise awareness about the case against 15 people who have been waiting nearly four years to go on trial following the October 2007 raids.
Co-organiser Ben Knight said the artists were trying to test the feasibility of an alleged plot to assassinate former United States president George W Bush by launching a bus from a catapult.
The artists tried several times to catapult pillows painted as school buses at a man wearing a mask in Mr Bush's likeness.
None of the pillows made contact with the target and the artists resorted to throwing pillows themselves.
It had proved difficult to successfully launch something from a catapult in a way that could cause a fatal injury, Mr Knight told NZPA.
"It did about as well as I think it would have if it was really attempted ... so we feel like we've done a fairly accurate job of recreating the situation -- kind of like a myth-busters exercise."
The stunt marked the opening of an art exhibition on the police raids at the Garrett Street exhibition space in Wellington.
