So far, we have examined a large variety of microtonal instruments. We have yet to discuss the keyboard and its role in producing microtonal music. In some ways the piano style keyboard is the victim of its own success. Its twelve keys per octave arrangement has become so common that many have forgotten that there are other alternatives, but imagine what you could do with this alternative keyboard controller from H-Pi Instruments.
This keyboard features an impressive 211 keys per octave. I can't imagine a situation where this wouldn't be sufficient. This same company also sells the Tuning Box, the world's first microtonal midi converter. You can use it to retune electronic keyboards or software synthesizers. It can store over 500 tunings. This is a great idea. This could save a person a lot of time and money shopping for equipment with microtonal capabilities.
If this all sounds new and unusual, you might enjoy visiting their instrument galleries that feature a long history of keyboards capable of playing more than 12 notes per octave. For example, here is a modern reconstruction of a sixteenth century harpsichord that has 36 keys per octave split between two manuals.
Here is a closeup of a 22 tone just intonation harpsichord keyboard with unusual split keys.