A mock wall will be built across part of the Irish border by protesters angered at the prospect of a hard Brexit.
The theatrical gesture on Saturday will be the centrepiece of a Co Down demonstration against future checks.
It is expected to attract up to 1,000 people, organiser Declan Fearon said.
If the UK leaves Europe without a deal the free-flow of goods could be disrupted by the creation of a hard frontier on the island, the European Commission has said.
Mr Fearon warned that local people would not allow the progress of the peace process to be dented by a political dispute over the backstop.
He said: “People won’t stand back and allow anyone to take us back to where these communities have been.”
Tonight we leafleted the Barcroft area with this leaflet. Brexit will be a disaster, ANY hardening of the border cannot be tolerated! I’ll be supporting The Border Communities Against Brexit on Saturday 26th 3pm #Brexit#communityprotest#newrypic.twitter.com/380xw1fLe0
— Sarah McAllister (@SarahJMcA) January 22, 2019
Mr Fearon, spokesman for Border Communities Against Brexit, criticised DUP leader Arlene Foster as “disingenuous” after she said there had never been a hard border.
“To even contemplate bringing those communities back to that, we have no intention of sitting idly by and allowing this to take place.”
The theatrical protest will involve local people, nurses and bricklayers, passing through a gate in the “wall”.
Mr Fearon added: “It is just a little dramatic scene of what life might look like.”
Security towers manned by the British Army in the hilly and remote area near the city of Newry were decommissioned in 2003 as it ended conflict-era operations in Northern Ireland in support of the police.
The Irish and British Governments have said they want to avoid a hard border after Brexit, and multiple sources have said Brexit should not prompt a return to violence.
Some security sources have argued that if customs checks are put in place then police will be required to protect them and that could leave officers at risk from dissident republicans.
The Police Service of Northern Ireland has received extra resources for Brexit but have officially envisaged light-touch community-style policing.
Dublin’s Foreign Affairs Minister Simon Coveney this week said it would be difficult to avoid installing new infrastructure following a no-deal Brexit.