This is a wall mountable housing for a DS18B20 PCB (Arduino). Version 4 has been printed in PLA and solves a serious issue with reading accurate ambient temperatures. The previous version was incorrectly reading internal wall temperatures.The new vent allows more accurate temperature readings and also allow included on board LED to be visible during operation. DS18B20 board clip into the housing. The housing then fits snugly into the base. Original Project: http://www.raspberrypi.org/forums/viewtopic.php?f=37&t=24115 I would suggest using supports during the build process to ensure dimensions stay as accurate as possible. A 30mm hole needs to be drilled in the wall to accommodate the base.