Gray said:
What sensor is that? What does it do?
It looks like a Wyze Sense Entry Sensor. It’s triggered when the two parts are more than half an inch apart. I wouldn’t recommend putting it on a garage door though, because the metal might mess with it, and it’s easy to tamper with from outside. There are better sensors specifically made for garage doors.
Brilliant hack, man!
I 3D printed this part, and it’s been working like a charm for 18 months now. Check it out: https://www.thingiverse.com/thing:4200241
This hack is awesome!
But what if gravity stops working? 
You could also add a more modern garage door opener like a rATGDO for full automation and sensor support.
Would this work with MyQ?
Or you could just buy a YoLink garage door sensor. Simple and made for this.
Alright, looks like I’m heading to Home Depot!
Looks like a Vivint door/window sensor. Vivint has a tilt sensor that’s better for garage doors.
Now that’s a neat idea!
Really smart solution!
I did this same setup with SmartThings at my old place.
Not sure why this is necessary. Everyone’s saying it’s clever, but what’s the real benefit here?
This is awesome, thanks for sharing!
I think this is a bad idea. It’s overly complicated and prone to failure. Just use a tilt sensor or something simpler.