All keyboard instruments can be converted to MIDI controllers or into complete MIDI systems containing the controller, expander, amplifier and even speakers such as the instrument shown in the video.

The limiting factor is space.

Currently we are working on a new system with radio link and webpage control of instrument parameters.

The MIDI concertina shown in the video here is complete and has stereo speaker output built into it.

It has a similar but more advanced construction to that shown below.

MIDI concertina construction

MIDI concertinas can be constructed from scratch.
The one shown here is CNC manufactured from plywood.
The mechanisn is traditional and the buttons turned from Delrin.
There are no reeds and this particular one has headphone output only.