Thank @DrYAk @The Kit @Venemo @locusf and @zeta for all the information. I need to study them...

BTW I have updated the title and the 1st post, to make the discussion matching the topic.

Also we have kicked off some structural design, and work on changing PCB. (@DrYak To answer your previous question, the PCB will be changed slightly to fit the keyboard connection and a hall effect sensor for the slider.)

Structural design is also not easy on this one... I want to maintain the looking that we loved, and also make it metal.

Will share more pictures through out design progress. Keypad will be re-designed as well. From feedback of Moto Keyboard Mod, the majority seem to prefer offset QAZ keys like PC rather than them on top of each other, the Nokia style...