So this is a sketch of what I want to build (my design and my artwork, deal with it
).

The box would be made using a cash box and an old PC power supply. I have the charger and the power supply but haven’t bought the cash box to house it yet because I’ll need either a dremel or someone who has a small metal shop to build it.
The wires aren’t showing because SketchUp (which is pretty slick) doesn’t make that too easy. Or I haven’t figured out how to do it right, yet. Hmm… well, I could put up an image of the back, but suffice it to say that there’s a cutout so that you can plug the power into the old power supply. The green divider is to separate the charging batteries into their own fire-resistant section.
Oh, and the sketch uses actual measurements. The box needs to be at least 4" deep, 13" wide and 10" deep in order for things to fit properly.