Earlier quoted context omitted.
The answer to that is to make your own and hand-solder wire to the switches.
The thought has occurred to me - and I wouldn't mind a thumb-trackball on the right hand, either. Design in the physical world is well outside my wheelhouse though - is a keyboard an approachable project for somebody who hasn't done woodworking/machining before, or would I be better served working on smaller projects first?
And /r/ErgoMechKeyboards on Reddit is a great community for understanding what you're trying to achieve.