I've corrected the error that I had on the thumb pad. You can grab the latest source including all the kicad files from here -- use the snapshot link to get a tarball:
There are three different boards to make: hand, thumb, and control.
Out of curiosity, what kind of layout were you thinking about for a 1/2 hand? I did start thinking briefly about making a chording version but I didn't get very far on that. The way I saw it the options were ASETNIOP, BAT, or FrogPad. Also TMK doesn't really support the kind of chording you'd need so you'd probably have to roll your own firmware. If you just want some type of macro board for audio or video work then that would be totally possible using what I have.
As for the case, I would recommend not using a router -- it does a horrible job. I've since cut a new top for my ErgoDox keyboard with a scroll saw and it's much better.