This is a case for the [Protractor Proximity Sensor](http://www.robogao.com/protractor "Protractor Proximity Sensor"). Not only does it keep the Protractor safe, it also helps shield the sensor from ambient light to maximize its usable range. This should be made from a black material to minimize reflections. It is better to not do any post-processing - leave the finish rough as this will help minimize light reflections. It is recommended to fine tune wall thickness in the attached OpenSCAD file to work best with your printer setup. The case shown in the picture was printed at Shapeways using PLA, and the model should work well for any FDM printer.

The [Protractor](http://www.robogao.com/protractor "Protractor Proximity Sensor") is a proximity sensor that tells you the angle to nearby objects and open pathways. It is super useful for robotic applications such as Mini Sumo, Bulldozer, Object Collection, Obstacle Avoidance, Maze Solving, and many more.

Learn more about the Protractor Proximity Sensor at http://www.robogao.com/protractor