Suitable for beginners and experts alike, this kit comes with over 250 components including a development board that’s compatible with Arduino Uno, 1602 I2C LCD, motors and ultrasonic modules.

Instead, it relies on an ultrasonic distance sensor to detect a hand (or foot) waved in front of the door. An Arduino Leonardo runs the show, sounding a buzzer when the ultrasonic sensor is triggered.

With a standard old HC-SR04 ultrasonic sensor, an audio module and a servo to drive a custom gauge needle he’s made a device which can warn people around you if they’re too close for comfort.