I needed a case to mount my Arduino Nano in, and I wanted to be able to see the LED and have it all stay together with a couple screws. This works well, I printed the top with translucent black so you cannot really see in but the LED clearly shines through. The little square column in the center places pressure on the board to keep it from moving without adding additional hardware. There are standoffs in the bottom that the board rests against and they allow all of the pins to be used. There is also a cutout in the front for the Mini USB to go through.
This was for a current sensing project i did, the Green LED comes on when a certain amount of current passes through the sensor and it signals my home automation system.