Ahhh.....THAT'S how those things work.  I've never seen one. Now that you describe how it works, I can see it in his picture in post #9.   So I'd assume multiple colors also gets a little heavy, too. potentially.
Maybe I will end up having to troll ebay.  Grrrrr....

But then, I could always just fork-out for another Tamiya body........  I like it, a lot....but, ouch!