This is Teenage Engineering’s amazing OP-Z, a tiny, TV-remote-size synthesizer and sequencer that has no screen, and yet manages to pack in a range of features that make users of “real” music hardware and software jealous. And if you do prefer working on a screen, you can hook it up to your iPhone via Bluetooth and use that.
OP-Z pocket synthesizer uses the iPhone as its screen

Photo: Teenage Engineering