Another Free Map Product Available on DriveThruRPG
I spent an hour or two putting something together, but that wasn't what the GM wanted. He wanted a computer program or app that would just automatically put overlays on his maps.
What I came up with was a huge 60" square PNG overlay labeled from A1 through to BY68. Just because he didn't want it I figured that maybe someone else would. The original one was black on a transparent background and I made an inverted copy of white on a transparent background.
If this is something you might find useful, go ahead and give it a download. The price should be a bit on the favorable side......