Looping is one of the fastest and most intuitive ways of music-making. It's always been great for improv and invention, but why not try it with MIDI messages this time?
The Bastl Midilooper is an experimental device that will help you do just that. It listens to control information about notes, dynamics, and other parameters, and it loops them in a way an audio looper would process pieces of audio. Since the MIDI loops remain in the control domain, many other processes can happen simultaneously on top of them - so you can explore timbre modulation, envelope adjustments, and way more.