Thanks guys - obviously, mainainence is an issue so that was one of the reasons to want a hinge (or some other way to acces the innards) but also, I want to make it a cross - platform control.
When it is built I will use some barrier strips to connect everything up and to start with, I will hack some ps/ps2 controllers (Being cheap, I was thinking of finding some original psone controllers without the dual shock. Third party of course

). However, I would also like to hack some dreamcast controllers as well, but may not do either of these until the construction is finished.
I figure that if I have the buttons wired up to a barrier strip then it will be a relatively simple matter to hack a few pads, solder them up, and then mount them and connect them.
That's the theory anyway. But then, I suppose that a removable base would be fine for that too.
Does anyone know of any projects that used a hing on the base?
Thanks - Gopher
p.s - great point Xphile - hadn't even thought of the 'seam' problem!