The last tray I made we used wheelchair batteries. The tray measures 5.25 x 19.75" in my reference one and I make them out of some rugged angle iron that will keep those lumps of lead in place better than sheet metal. You can slice end handles off, put fake or real top ropes on, paint them and stick soda bottle caps on top. Sal sells Rebat labels and even replica batteries which look pretty good. Some battery numbers to look up are Line G-35 and UB12350. Here's a link to get you going
http://www.aircraftspruce.com/catalo...s/gillbatt.php