I removed the plastic trays from the inside of the box, and then painted the inside matt black. The Battle boards are made from 5mm thick foam core, divided into 30mm squares, 8 by 10 in total. The bottom three pictures above show the basic boards resting on the box, with a copy of Bob Cordery's Portable Wargame rules They are second from bottom on the linked page. I have always admired Bobs elegantly simple rules. The only issue that I have with them is an aesthetic one, the use of gridded terrain has always struck me as being to close to a board game from a visual perspective.
My aim with this project is to see if I can create a portable gridded wargame which doesn't look like it is one, if you get what I mean. The top picture is a sketch I made on my iphone, it gives a very rough idea of how I hope the terrain boards will look.