"Avoid touching your eyes, nose and mouth" after washing your hands or using hand sanitizer (assuming you can find hand sanitizer anywhere). This is easy to say, hard to do. This device (sort of like a watch) attaches to your wrist using a rubber band. When your arm rises in a "face touching direction, " a tilt switch activates a buzzer to let you know that your hand is trying to get you into trouble.
Normally I use 3D-printed parts, battery holders, wire wrap wire and such to make a project. For this device, I'm aiming for simplicity so that more people (anyone who can solder) can copy it if they desire. The body is made from cardboard (hey, I wrote a book about cardboard construction).
Start with the wristband, a piece of sewing elastic 1" wide by 9" long.
Add 1 1/2" of velcro (the back side is sticky) such that the band can be closed on a wrist.
Cut a piece of cardboard, 1 1/2" by 1 1/2".
Tape the cardboard to the elastic (like a watch face to a watch band). I use foil duct tape.
Cut two 3/4" by 3/4" pieces of cardboard.
Glue the 3/4" pieces, one on top of the other, to the 1 1/2" square.
Cut a 2" piece of #24 wire and strip the ends.
Solder one end of this wire to the negative (short pin) end of the 3 volt buzzer.
Cut a 1 1/2" piece of #24 wire and strip the ends.
Solder one end of this wire to the silver color (long lead) side of the tilt switch.
Solder the other end of this wire to the long pin on the buzzer.
Cut the excess wire from the silver end of the tilt switch.
From the negative side of the buzzer (black wire in my example), tape the end of the wire to the negative side of the CR2032 battery.
Tape the brass colored end (short lead) of the tilt switch to the positive side of the battery.
Secure the buzzer assembly to the 1 1/2" cardboard assembly using a piece of tape--3/4" by 3".
Secure the buzzer using another small piece of tape.
If you find the buzzer annoying, then you can use an LED in its place. The LED needs to tolerate 3 volts (white, blue, flashing--not red).
Since you will probably have a surplus supply of tilt switches, make a few of these devices for your friends.
To minimize the parts required, the battery is taped into the system and not easily exchanged, but it should last a long time if not left in a continually on position.