I hope that you, Goran, appreciate/realize that I (and other concertina makers) are unwilling to spend massive amounts of effort to see if your ideas are viable. YOU need to put in the effort sufficient to convince us to take appropriate steps.
Thank you for the drawings, Goran. However, the reason I wanted actual scale drawings was to see if your design suggestions would actually work.
You probably understand that I will not waste time in a complete construction drawing as not intending to make a 'product' myself...
I regard making prototypes from insufficient design to be a vast waste of resources and time. Concertinas are INCREDIBLY complex. Not until you try making them yourself will you have a reasonable idea of how much knowledge, skill, and time designing a concertina takes.
I see no major difficulties to *make* a similar instrument...but i would not expect it to be a hit from scratch. 10 prototypes or so ahead one knows better...
Both I and Frank have listed many specific difficulties that can only be overcome with scaled drawings rather than conceptual designs. For instance you said:
I'm willing to try sorting out a bit more 'conceptually' what can be done in different ways...are there any specific difficulties?
...you can simply applicate solutions used for bandonions/chemnitzers and alike for the mechanism and on the way modify or improve them
which is not readily applicable for the quality of instruments we want to produce. Bandoneon/chemnizter actions are inherently uneven and not well balanced, have excessive friction and wear, and take up a lot more room that concertina actions do.
Even not considering any of this, there is still the issue of locating all the action parts to be able to work given your conceptual location of the keys and reedblocks. Your conceptions don't address HOW it can be made to work. I can't imagine how. That is why we need scaled drawings.