Here is a VR title that lets you finger paint music in the air. Virtual Music Machine lets you use a Leap Motion Controller in addition to your VR headset to express yourself in a virtual environment. Simply dip your right hand into a paint bucket to pick up an instrument and make a fist to paint music in the air.
According to the developers, low notes are near the ground and get higher pitched as you move your hands upwards. This title works on HTC Vive and Oculus Rift.