An example of a simple electronics solution and "homebrew project" by a radio amateur in Germany relevant to a very important issue of today. The news article is in the German language but translates well with Google. The instructional build web site is in English. Both links and others of interest are embedded in the bold text below. If only there was something inventive to convince the public to wear facial protection diligently. 73, John, WØPV Physical-Distancing-Warner mit Arduino - Wenn einem fremde Leute zu sehr auf die Pelle rücken, hilft der Covid-19-Abstandswarner: Ein Arduino und ein paar Zeilen Code halten Mitmenschen auf Distanz. Translation - If a stranger gets too close to you, the Covid 19 distance warning helps: An Arduino and a few lines of code keep people at a distance. (Article author Carsten Meyer) Actually a simple idea: Take a commercially available ultrasonic distance sensor of the type HC-SR04 , an Arduino Nano and a couple of LEDs and use it to build an electronic distance warning device. It sounds the alarm when a person approaches less than the minimum distance - in a nice way: the LEDs then either show a friendly or sad smiley. In addition, a buzzer warns that the distance is too short, and the more excited the shorter the set distance is. Radio amateur @DL1EKM (personal website link) published the project on the DIY platform Hackster.io.(an English link) The circuit does not need more than a handful of components; the material costs should be limited to 10 euros if you use one of the inexpensive Arduino clones. In addition to the parts list, circuit diagram and source code, DL1EKM also offers the PCB layout for download on its project page. Incidentally, based on the infamous Hassler by (American engineer) Bob Widlar (son of a ham and brother of todays W8ERI), the device should also be interesting for chronic misanthropes and Asperger's autism in post-Corona times.