I’ve been working on the mechanical design and electronics.
Some inspiration I had this week:
I liked Mark’s MixTape on-PCB touch pads: http://wiki.openmusiclabs.com/wiki/MixtapeAlpha?action=AttachFile&do=view&target=mixtape2_sch.png
Nan-Wei suggested using small connectors: http://www.jst.com/home20.html