I wanted a slim case for my Geekcreit® ATmega328P Nano V3 (a copy of the Arduino Nano board you can find on Banggood).
I also wanted a case for situations without pins, but an output cable directly soldered on the board : I did this one.
No components footprint to be compatible with all boards, a 3mm cable output, a window to see the LEDs and a reset button, simple and beautiful ;-)
0,1 layer and 100% fill will do it clean.
The author hasn't provided the model origin yet.