Before Bendy Walls... before Dwarven Forge... before Hirst Arts... there was...
Dungeonworks(TM) Magnetic Dungeon!
The corners of each wall section were mitred at 45 degrees so you could make convincing corners and but walls together to make corridors. Door archways were also included in the set, but there were no doors themselves. As you can see I added some resin cast doors to a few of the walls in my set.
foamcard 3D dungeon, a winning combination in my opinion.
The miniatures end up being crammed into a tiny area and the board can only handle a maximum room size of 50'x50'. I guess they were expecting you to buy more than one set, but it was too heavy to carry around compared with a box of cardstock floorplans, not to mention the price.