Ive been thinking of this also, I would love an A1200 case, a bit higher for more room, maybe a bit wider on the left side for easier placement of more HDDs, for me it could be wide enough that the PCMCIA card just sticks out as on laptops (the the end of the card) so a bit space to take there.
If making them a bit bigger I would also love a slot for slim CD, space for cooling at expansion slot should also be nice.
