There are numerous examples of applications where you need to make things move. We have earlier built traps for nest boxes, and here is another application where the researcher wanted a twisting mirror. A relatively easy way of achieving this is to use a servo (same type are used in model aircraft) where you have a motor that twists a certain angle with good precision. The motor input is a square wave (PWM), which could be tricky to create. It is therefore convenient to use a programmable microprocessor to create the signal. Building and programming these kinds of devices used to be quite complicated, but since the introduction of the Raspberry PI and the Arduino, almost anyone can program such a device. Here we are using an Arduino Uno to give the user the possibility to change speed and angle. The Arduino platform then creates the suitable output to control the servo.