Gyromin is a handheld musical instrument loosely based on a theremin. It uses the EV3 Gyro Sensor to track rotation, which controls the pitch and volume. There are also three buttons intended to switch octaves, but one or more of these could also be used for effects such as reverb.
While I am too late to enter the "Music to our ears!" LEGO Ideas contest, it inspired me to create a functional musical instrument from Legos and here it is. I have been fascinated with programmable Legos since the early 90's, but have never owned any. When I found LEGO Digital Designer (LDD), I was finally able to play with the toys of my childhood dreams. I have a box of 30+ year old Legos that I used to mockup the sensors and started building the instrument around them. Then, I rebuilt it in LDD. If this gets enough interest, I might improve the ergonomics and aesthetics by building the Gyromin entirely from LEGO Technic.
I think this set would be a fun way for students of any age to explore science, technology, engineering, arts, and math (STEAM). In addition to building and possibly modifying the set, there are hours of fun to be had making music and countless possibilities via the ability to program the EV3.