A simple actuator from a small, but full metal geared motor: 12V motor http://s.click.aliexpress.com/e/bTtwpF3a or 24V motor: http://s.click.aliexpress.com/e/EBW8dAY.

I use 4 RPM version, but 1 RPM to 4 RPM is OK. Smaller RPM is stronger.

I designed this thing to remotely open and close a small window (30x45cm) in the attic using mysensors relays (https://www.mysensors.org/build). Attention: the actuator PLA parts rather aren't resistant for a storm or a strong wind! I plan to use a metal rigid flange connection on the motor shaft.

Additionally this thing needs: 2x micro switch (6mm height): http://s.click.aliexpress.com/e/bWFlxPYy 2x rectifier diode (ex. 1N4007) wires 2x M5 bolts and 4x M5 nuts (to join a crank with the arm and the window bracket) 2x M4x10 bolts and 2x M4 nuts (to regulate length or arm) 5x M4x10 bolts and 5x M4 nuts (to join the motor base and the metal plate) 4x M3x7 bolts (to join the motor and the motor base) 1x M3x1 bolt and 1x M3 nut (to fix the crank and a motor axis) The universal metal plate (thickness min 3mm) with holes (20mm hole offset) from DIY store.

FreeCAD files included. The simple mechanical simulation in sketch okienko-simulation.fcstd to derive a place to mount window bracket (a distance from a window hinge) and length of arm.

The switches and diodes limits rotation to about 160 degrees. The electrical connection diagrams attached. The window is controlled by change polarity on power lines. To open or close manually you can disconnect the arm from the window bracket.