Some of you may find this interesting.
Amiga user Egon Kohlschütter has managed to fit both a CD-ROM and an IDE harddisk into the A1200's original case. The idea is to move the harddrive to the right of the case (to the position normally occupied by the internal disk drive) and put the CD-ROM to the left side of the case. The floppy drive had to be removed to gain the neccessary space (Egon uses an external drive now) and the case had to be slightly modified.
Pics and info on how to do it yourself are available at the link provided.