I located a scrap of plastic, and cut it to fit inside my battery hold down. Then I used a 1" hole saw to cut holes for the battery posts and 3 holes where the caps would go on a 6 volt battery. I cut the necks off 3 oil bottles, leaving a rim on the bottom. The bottle necks were a tight fit in the 1" hole, I used a rubber mallet to drive them in. Once in place they are retained by the ring the cap seats on and the rim I left on the bottom.

A Willard sticker completes the look. I'll be changing the caps to red or yellow, all I had around were black or gray.