Kind of like you see in the lower decks of the first “Alien” movie or in other sci-fi movies, or the mechanics of how hypertubes already open and close. A high-tech-looking square-framed Mechanical Iris doorway.
It could be mounted in full size to an 8x8 vertical area like a massive stargate-looking affair, or a smaller one could be about quarter-foundation size (2mx2m diameter) and come in 1,2,4m depths to use like mechanical access corridor batches.