To date I have designed three version of the Keyboard Development Module, each having slight changes...

The first provided four test RGB leds and used a 30 pin connector and a three pin connector for the RGB, the second removed the RGB leds, simplified the Boot, Reset switches and changed to a single 34 pin 1.27mm connector.

The third and last version, is identical to the second but changes the position of the connector making connection to the basic keyboard easier and more natural.

All three modules work perfectly for developing and testing QMK/VIA code but once you are finished your code development, I want to be able to use them on the actual keyboard. To this end I provide several basis keyboards containing all the necessary parts allowing connection to one of the modules.

All versions of the modules were tested and worked fine, but you have any interest in the module, I'd go with Version 2.0D. I have also included a design for a small converter board, it allows the module to connect to a breadboard... See: My Git and Adapter Board

The final version pictured below.

This is powering my current keyboard (along with the basic keyboard EN014)

It appears to be more cost effective to use a module as opposed to building a keyboard including the full electronics from the beginning. As you can hand assemble the keyboard as all components are pretty easy to hand solder and getting the modules fully assembled is cost effective, less than €20 and a keyboard PCB was about €10 each. 

The FR4 Plate cost about €5 but prices have since increased, appears I got a real bargain at the time (no tooling charges).