Use an ultrasound sensor to make music that can be heard from a little buzzer. There are two modes: Improviser mode and Theremin mode. In order to switch the modes, simply detach and re-attach the buzzer to pins 2-4 for Improviser or pins 5-7 for Theremin.

What you'll need:

• Arduino Uno
• HC-SR04 ultrasound sensor
• Three-legged 8 ohm buzzer
• Jumper wires and a mini-USB cable connection to the computer
• Tone.h Arduino library

Modes:

1. Improviser mode (buzzer at pins 2-4): Put your hand in front of the sensor and it will generate a low-pitched diatonic melody. Move your hand slowly away from the sensor, and the melody will go up in pitch. Each note will take 200 milliseconds (5 notes per second).

2. Theremin mode (buzzer at pins 5-7): Have the sensor face a wall at the distance of 50–100 cm, and it will generate a steady pitch. Get it closer to the wall and the pitch will increase. Get it further away from the wall and the pitch will decrease.

Control a WS2812B LED strip so that it flashes rainbow color and blinks when a tilt sensor receives a fast physical movement.

What you'll need:

• Arduino Nano
• WS2812B LED strip (individually-addressable and programmable)
• Three-legged tilt sensor
• Jumper wires and a micro-USB cable connection to the computer
• FastLED.h Arduino library