Smart Effector hook

This hook is designed to hold the Smart Effector in a Think3DPrint3D Kossel XL Plus if it is too heavy to stay on its position after turning the printer off.
Since this is the case after [mounting big fans to the Smart Effector](https://www.thingiverse.com/thing:2909853 "Smart Effector mounts for large fans"), I designed this hook.
You need two M10 screws as counter weight in order for the hook to stay "open" by itself. When the Smart Effector is in home position you can press the hook down and hold it in position until the printer is turned off. The Carriage Adapter then falls into the hook and its position is fixed. After the printer is turned back on it only has to be homed in order to let the hook release the Carriage Adapter again and open itself.