A WeMOS D1 MIni used to fire alert messages when a button is pressed
Basically something my Mum can press to send an alert email to me when she is in trouble.
I fitted this inside a big red button I bought off Amazon. You could make your own button as long as you have two AAA cells to give between 2.5V and 3.3V.
Here's the schematic for the PCB. I haven't design a PCB for it since it's a one off prototype.
The Arduino sketch for it is included.
Enjoy.