The Theremin

Playing the Theremin is not an easy thing, it takes a lot of trial and error to work out where the hands need to go to produce the right sound.  This exercise is looking for a way to help people learn the Theremin, to help them know where to put their hands to produce the right notes and tell them when they are right.

Option 1: Visible lasers.
Using visible lasers which will help guide the player to where to put their hands.  Downside is that you could end up with a lot of lasers beaming about the device.

Option 2: A distance measuring device.
A distance measuring device which displays the results on a screen.  It would tell you what numbers you need to get from the X, Y, and Z axis and what you actually have.

Option 3:  A brace over the arm/shoulder.
A brace over the arm or shoulder which detects the hand and/or arm positions and provides physical feedback on where the player needs to move to be correct.  Downside could be if the device provides too much resistance and people get hurt - but I'm sure those bugs could be worked out in testing.

Option 4:  Air Cannon
An air cannon that blows air where you need to put your hand.  A similar idea to the visible lasers but perhaps harder for the hand to detect, the stream would likely have to be very small and once you are trying to detect the air from three directions, it might become hard to be accurate.

Option 5:  Colour
A similar set up to option 2, but the screen displays a colour, the closer you are the greener it gets, when you are far away it's red.

Option 6: Bubbles
Have a video camera in front and to the side with a screen to watch.  On the screen is a bubble where you need to move your hand to.  Get your hand to the virtual bubble and it pops, the next one appearing.