Optical Mouse Midi Cello
For the price of a video game, you can make your own Midi Controllers. My first one used two optical mice and an Arduino to make a cello type Midi controller. PVC pipe and couplers are used to make a flexible, build your own design type project. One mouse tracks a bow made out of some square dowel. The other is attached to a piece of PVC pipe so it can slide up and down a round dowel providing pitch and CV (filter) . A simple Arduino controller allows the two mice to be used independently. Easy to get parts from your local hardware store. Simple tools needed. Endless possibilities. Add 6 Infra red leds and phototransistors and you can make a guitar. cello style - see below, guitar style - https://youtu.be/GsYFa_vsnms Switch up the Arduino for Bluetooth Midi.