I have made an "all off" button for my Philips HUE and Nexa equipment. To be able to turn off everything when we leave the house. It is based on an arduino compatible WeMos D1 Mini with a button shield. I added two LEDs to give some visual feedback on the button press and when it is working because it is sending signals to all the devices.
There are three versions of the box. One with the button only, one with the LEDs in addition and one with button, LEDs and the text "ALL OFF".
Link to model and an option to download more file formats:
And if you are very interested. Here is the not so well documented code for the WeMos D1 Mini: