Since we gamed before I had a computer. I came up with these floor pieces made of manila folders.
Later on I made some of white poster board. I included one, but it didn’t scan very well.
Each large square is 2 inches wide and is divided up into thirds. This piece represents a 10 foot wide corridor x 40’ long.
I have over 200 of these in various lengths and widths.
I made this with drafting tools left over from university. T-square, ruler, drafting pen, India ink. Along with a cutting board, a knife that can cut manila folders, a craft knife or craft scissors would do.
I used a soft lead pencil to draw the preliminary lines. Cut them out, then inked the lines in.
To keep them from sliding around the table, I bought a 5’ long and 2’ wide scrap of felt from a craft store’s ‘cheap stuff’ bin.
Place these floor tiles on the felt, place the game miniatures on top of the floor tiles.
You could do the same thing with plastic mats.