Electronic module chassis for Raspberry based robots

I looked for a flexible concept for adding and removing electronic modules during development of a RaspBerry (1) based robot. I finally decided to use my 3D printer for creating a chassis allowing to mount multiple modules on different positions. The square shaped mounting holes are designed for plastic screws (e.g. Sicaplas). I added two model files for the chassis bridge where one of them has a removable bottom plate for better contact to the printing bed.