I made a super simple way to create maps for in-person DND campaigns.

The floor pieces are 6"x6" and are made up of 36 1"x1" tiles . I also made walls that fit perfectly into the grooves of the tiles. The walls do have varying heights of 1"x1" , 1"x2" , 1"x3" , and 1"x4". Even with the 1"x4" walls supports are not needed

If I want to make a long corridor I place the walls with the 1" side facing out so its not seen by characters.

The 1"x1" walls can be made a different color to differentiate doors from walls.