The main purpose of this device is to make people aware of how many times they touch their face (eyes, nose and mouth) and why we should avoid doing that because of the Corona/COVID19 virus.
With this device around your wrist it plays an alarm signal or lights up an LED when you raise your arm. If you want to build one yourself, check the GitHub page:

https://github.com/leonvandenbeukel/P...

Of course you can make two of them if need, one for each wrist. When using it on the right arm you have to flip the PCB and the cover.

Somebody that made a similar device but is taking different approach, check it out also:
   • Open Source DIY Face Touch Alert Device  

Usefull advice from the WHO explaining to avoid touching eyes, nose and mouth:
https://www.who.int/emergencies/disea...