In a garden in a quiet cul-de-sac in north Armagh, a nondescript brown shed contains the Irish republican version of the Imperial War Museum.

The private collection contains the toilet-roll holder from the room where IRA hunger striker Bobby Sands died in May 1981, letters from supporters to Sands, an original rebel uniform from the 1916 Easter rising, secret communications smuggled out of the Maze prison and a 19th-century cell door from London's Pentonville jail where Irish republican prisoners were incarcerated. There are piles of original black rubber bullets fired during riots in the early 1970s. There are even Airfix-style models recreating the Maze prison.

Its owner – who lost close relatives during the Troubles – is so security-conscious he doesn't allow his name or the museum's address to be published. All visits are arranged quietly on the "republican grapevine", but have managed to bring together former republican rivals who were once deadly enemies. Former members of the Provisional and Official IRAs as well as the Irish National Liberation army have met again during private visits to the collection. Earlier this month the surviving "hooded men" – republican suspects used as "torture guinea-pigs" by the British army early in the Troubles in 1971 – gathered together for the first time in a reunion at the museum.

The Guardian was given access last week to the privately owned museum which also hosts visits by foreign tourists and even some Ulster loyalists. And the "curator" of the "History House" revealed that officials from the Republic's National Museum of Ireland in Dublin recently paid a visit.

"They wanted to buy some of the artefacts, but I wasn't for selling," the owner said. "I want this museum to remain private yet accessible and completely free. I would never charge a penny to those I allow to view it."

He said an Irish-American visitor this year at the end of a tour pulled out a chequebook. "He signed the cheque and left the amount in dollars blank and said I could put any figure down."

But the owner explained that he wouldn't "sell the artefacts either to rich private collectors or the state".

Over more than two decades he has amassed a vast array of flags, badges, posters, the casings of bullets fired from IRA rifles during the Troubles and even a crystal radio set smuggled into the Maze so that the H-Block prisoners could track the news of Sands's triumph in the Fermanagh and South Tyrone byelection the month before he died.

The collection also includes an original copy of the IRA's so-called Green Book, the code of practice for armed republicans drawn up in the 1950s. From the same era, the owner of the "History House" has put on display the steel cups IRA prisoners drank from inside the Victorian Crumlin Road jail in Belfast.

Among other artefacts are two Celtic-style crosses. Both were made from matchsticks because prison authorities denied the IRA inmates access to woodwork material. One comes from an IRA man held in Crumlin Road jail in the 1950s; the other is from the 21st century and was hand-crafted in his cell by a republican dissident prisoner.

"These crosses show how Irish republican history sometimes goes in circles," the owner said. "In the 50s, the authorities would not give republicans wood for them to make Celtic crosses, Irish harps and other Irish traditional crafts. They cited security reasons but the prisoners showed ingenuity by using matchsticks instead. They are citing the same reason today in Maghaberry jail [where prisoners are challenging conditions], and the dissident republicans are resorting back to the same tactics as their predecessors."

As if to underline his point, the owner displayed two more artefacts from his museum. They were a poster from the 1970s highlighting the case of Martin Corey, a Provisional IRA prisoner and Lurgan republican and a huge Irish Harp he made with his own hands while incarcerated in the Maze. He added that Corey is currently back in jail, locked up in Maghaberry, this time as a prisoner on the Continuity IRA wing.