Stone was stopped at the door of Stormont in November 2006
An art expert has said that having real nail bombs could "come under the ambit" of performance art, as long as there was no intention of setting them off.
Peter Bond, a senior art lecturer at St Martin's College, London, was speaking at the trial of Michael Stone, 53.
Stone denies attempting to murder two Sinn Fein leaders at Stormont in 2006.
Mr Bond told Belfast Crown Court that if an individual intended to detonate such bombs, "not for one moment" could that be construed as performance art.
As well as the charges of attempting to murder Gerry Adams and Martin McGuinness, loyalist Stone denies 12 other charges of possessing nail and pipe bombs with intent, possessing three knives, an axe and a garotte and having an imitation firearm on 24 November 2006.
In his evidence, Mr Bond, a professional performance artist stressed that in performance art, the most important thing was that people were not harmed.
Giving evidence on his own behalf, Stone had claimed the whole incident was performance art, designed to send a "proverbial rocket up the backsides" of the politicians.
He claimed that all the items he had brought with him on that day had their own symbolism in what he described as "an installation".
The trial continues.