I was thinking about this for a bit and I think if you can find a old computer power supply you could gut it and use the case by putting some of those connectors like you see on power supplies and such. Like the type you see that you can put a banana plug in and also unscrew it so you can put a C clip or a wire under it and then tighten down. I think that would be pretty cool.

What i'm trying to say I guess is that you can run your primary 12 volts in and then put 3 or 4 sets of connectors so you can plug and unplug chargers as you see fit. Also this would work well for nicad or nmh charging also as you could plug in different chargers at the same time without having to sacrifice charging one or the other. It could come in handy to charge your radio batteries at the field also.