I also didn't add the slot for the PCB, mostly because I wasn't sure of
the size, and I didn't have the appropriate cutter lying close by.  I
have a couple thoughts on that.

hmm me too: a CNC lathe would do the trick.  the slot is essential in
one of the parts for access to the PCMCIA eject-button.

http://hands.com/~lkcl/eoma/kde_tablet/3dcase/microdesktop_model2_corner.stl

Yeah.  At the complexity of the inside you have there, I don't see
anything short of CNC that that could reasonably do the job.  Those sharp
inside corners are hard, but it looks like a single cutter pass can
probably run past far enough to work if that direction were taken.