It needs to have velocity and aftertouch on the lower keyboard.
The neck keyboard should be very flat, like buttons, but more than just a printed plastic film. The neck wouldn't have velocity, but still needs to have aftertouch. The pitchbend bar is raised for the option to put a thumb under it or palm down. It should be pretty stiff.
Any extra standard midi controller functions that I forgot can go on the back of the body.
I was thinking that there could be either different styles or just a removable blank matte cover plate that you could customize.
Kinda like some cell phones.
My style ideas are:
Euro-Future, Rusted Cyber-Blood
Gloom Sexy. London Garage
57 Cherry, Mahogany Pearl
Rhyme & Bass, Blue Soul
Black Tie, Video Killed the Radio Star
There should be a contest for who can come up with the coolest designs based on these names.