Amazon.com: PreSonus Atom SQ Keyboard/Pad Hybrid MIDI Keyboard/Pad Performance and Production Controller Hardware Control Surface with 32-Velocity and Gravity Magnet Phone Holder and Pair of XLR Cable Bundle : Musical Instruments
Old Phone Becomes MIDI Controller | Hackaday
Midi Controller - Remote & USB on the App Store
Amazon.com: Arturia 37-Key KeyStepPro Controller & Sequencer USB/MIDI/CV Keyboard Controller, with Aftertouch KeyStep Pro with V-Moda Forza in-Ear Hybrid Sport Headphones and Gravity Phone Holder Bundle PK1 : Musical Instruments
Control MIDI and Ableton from your iPhone, Android for handheld music - CDM Create Digital Music