The 2x6 I2C pin connector is pin compatible with ftDuino and fischertechnik TX connectors. See the pictures for assembly details. A lightguide for the module's LED is optional, just drill or push the hole in the top part fully through and insert a short length of transparent 1.75mm filament. If you like my design, please leave a comment, upload a make, or favorite it. Find my other fischertechnik desings here at YouMagine (https://www.youmagine.com/juh3d/designs) and on thingiverse (https://www.thingiverse.com/juh/designs).