SP84 Split 75%
this Keyboard is a bit old but I never used it, and I built it my self, it came with only the PCB and the case the rest of components were hand soldered, it's also customizable with a software called BootMapper.
it uses a USB-Mini connection between the left/right parts and also to the computer, all cables are included, the mechanical switches are Soldered so you can't change them but you can still change the keycaps if you don't like the included keycaps.