Let it hit your red LED and you’ve lost ... Inside the cool laser-cut box is an Arduino Uno and a 9V battery, plus a current-limiting resistor and the all-important buzzer.

Arduino Camping Light * Camping Light with a single push button switch to control the light output between off, dim, medium, and high brightness * Test Configuration: MCU: Arduino UNO R3 IDE: Arduino ...

Figure an Arduino ... that buzzer says "current consumption: 20 mA" These piezo buzzers can be corrected directly to a DC supply. There is no need for a current-limiting R (as for an LED).