The FAC system is a set of components that can be combined to create a mechanical project. You can think of it like a more grown up and serious version of K'NEX. It allows you to rapidly prototype and construct a device using a set of standard mechanical parts which you can then control however you want.
Wilbert Swinkles has designed this amazingly beautiful mechanical Rubik's Cube solver using the FAC system. The programming of the device was done by Maxim Tsoy, using a Raspberry Pi to crunch all the numbers and do the calculation.
If you watch the video below, you will see the amazing machine in action. It certainly looks the part, and is surprisingly fluid to say it has multiple degrees of movement. After you place the cube in the holder, it performs a scan of each side of the cube. It features 3 modified Colorpal colour sensors to detect the colours during the scan, and an Arduino Mini to do the movement.
Once the Pi has all the colour information it needs, it calculates what it needs to do to solve the puzzle. It doesn't take long for the grippers to start twisting the cube every-which-way, and after a short while, each side of the cube is one solid colour, and the holder clamps back together and the grippers remove. It's a really satisfying end to the process.