Is the 3000T's case made by Commodore, or was it stock from elsewhere? I need a side panel for one.
The case of the Amiga 3000T was actually modified from the Commodore PC-60 III (their top-range PC). I doubt, however, that this makes it an easier find. Those monsters are sought after as well, apparently.
Commodore was still fully functional when the PC-60 and 3000T were produced, so it is very unlikely a generic stock item from a third-party supplier.