Outside of straight up battery holders and 9v adapters they are not really a standard part and everybody will make things according to their whims. In industry said making will tend to be a press and a custom die which is not a cheap thing to make for a one off. They are also not the sort of thing that fails very often (leaked batteries being about the only case to occur in any great number) and so such things tend not to make it onto the spare part market.
I pulled apart a GBC to have a look. Nothing outrageous in a GBC but probably different enough that you can not just go searching in poundland or a charity shop for a donor item, assuming you want a good replacement and not a run some wires and glue it all in job). Anyway two things standing on the board and a strip on the other side to stick the batteries in series.
For a smaller thing you could consider getting something laser cut, or otherwise machined and punch/press your own holes and figure out ways to attach your own springs but that is still not going to be much less than just buying a broken one and cannibalising it. Given a bit of time it is the sort of thing you could make with a set of needle files and a piece of thin sheet steel (I checked one of mine and it was magnetic, not to mention it was soldered in so it would likely not have been aluminium).
If you want dimensions I can possibly help with that, though it might have to wait for when I am not falling asleep in my chair.