This is an old version. Please see version 2 of the in-wall sonoff light switch. Version 2 doesn't require the additional pcb and button. You can find it here: https://www.thingiverse.com/thing:2632463

After printing, you will need to insert the Actuator through the back of the Mount Plate and carefully force the tabs of the Actuator into the holes on the Mount Plate. Once you have the Actuator installed, it will be a little stiff and hard to move, but just work it back a forth a few times and it will soon operate smoothly.

You will also need to make up the PCB that holds the pull-up resistors and buttons which the actuator presses. I just used some perf-board and salvaged buttons and resistors to make it. The PCB should be shaped as in the image above because the sonoff's button and LED are rather tall and I wanted to make sure that the whole switch enclosure would fit inside the wall with the existing wires tucked behind it.

Below is my video describing my Sonoff In-Wall Light Switch. I also show how to install it in the wall, by replacing an existing light switch. One thing to note, the sonoff will not be able to replace a 3-way light switch, I explain this more in the video.

I debated uploading this to a different site and charge $1 to download it. But ultimately I decided against that, as I am a big fan of open source and have benefited from it so much. So instead of paying for the .stl files, I would appreciate it if you would subscribe to my new youtube channel and share the video.

https://www.youtube.com/watch?v=XgzF7lwwa0A&t=49s