I got sick of hooking up two 6V batteries whenever I needed a 12V supply so I threw this thing together.
It has a 12V (red), 4V-7V (yellow), ground (black) banana plug outlets and an 89, 906, 555 and 44 lamp tester as well.
All mounted on a piece of left over wood from some arcade cabs I made up, even has t-molding.