Constructing the quadcopter hardware can be daunting; however, there are several excellent websites that can lead you through the process from component selection to build details and programming and controlling your quadcopter with a radio. The http://www.arducopter.co.uk/ website is a great place to start for those who are new to quadcopter flight. Go to http://copter.ardupilot.com/, which is another excellent website with lots of information.
For this project, you'll want to choose a project that uses the Pixhawk flight controller. There are other flight controllers that are significantly less expensive, but this particular flight controller provides easy access for Raspberry Pi. Here are some possible websites that can guide you through the construction process; http://learnrobotix.com/uavs/quadcopter-build/pixhawk/connecting-the-q-brain-esc.html, http://www.thedroneinfo.com/2015/06/06/build-a-quadcopter-with-pixhawk-flight-controller/, and http://www.flying...
