Battle Map

I have a large (A1) laminated offset-square 1" grid that I use as a battle map for D&D. It works great, being very quick and convenient to set up with a whiteboard marker, and it's very clear and visible to all the players (and me). However, it turns out that it's not ideal for exploration sessions, as even on an A1 sheet, a one-inch grid doesn't go all that far. And if the party go off in an…